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* [gcc r13-2546] analyzer: support for symbolic values in the out-of-bounds checker [PR106625]
@ 2022-09-08 17:47 Tim Lange
0 siblings, 0 replies; only message in thread
From: Tim Lange @ 2022-09-08 17:47 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:7a6564c9b277d9f93582605758d57457de696deb
commit r13-2546-g7a6564c9b277d9f93582605758d57457de696deb
Author: Tim Lange <mail@tim-lange.me>
Date: Wed Sep 7 17:41:28 2022 +0200
analyzer: support for symbolic values in the out-of-bounds checker [PR106625]
This patch adds support for reasoning about the inequality of two symbolic
values in the special case specifically suited for reasoning about
out-of-bounds past the end of the buffer. With this patch, the analyzer
catches off-by-one errors and more even when the offset and capacity is
symbolic.
Regrtested on Linux x86_64 and tested on coreutils, curl, httpd and
openssh as usual.
2022-09-07 Tim Lange <mail@tim-lange.me>
gcc/analyzer/ChangeLog:
PR analyzer/106625
* analyzer.h (region_offset): Eliminate m_is_symbolic member.
* region-model-impl-calls.cc (region_model::impl_call_realloc):
Refine implementation to be more precise.
* region-model.cc (class symbolic_past_the_end):
Abstract diagnostic class to complain about accesses past the end
with symbolic values.
(class symbolic_buffer_overflow):
Concrete diagnostic class to complain about buffer overflows with
symbolic values.
(class symbolic_buffer_overread):
Concrete diagnostic class to complain about buffer overreads with
symbolic values.
(region_model::check_symbolic_bounds): New function.
(maybe_get_integer_cst_tree): New helper function.
(region_model::check_region_bounds):
Add call to check_symbolic_bounds if offset is not concrete.
(region_model::eval_condition_without_cm):
Add support for EQ_EXPR and GT_EXPR with binaryop_svalues.
(is_positive_svalue): New hleper function.
(region_model::symbolic_greater_than):
New function to handle GT_EXPR comparisons with symbolic values.
(region_model::structural_equality): New function to compare
whether two svalues are structured the same, i.e. evaluate to
the same value.
(test_struct): Reflect changes to region::calc_offset.
(test_var): Likewise.
(test_array_2): Likewise and add selftest with symbolic i.
* region-model.h (class region_model): Add check_symbolic_bounds,
symbolic_greater_than and structural_equality.
* region.cc (region::get_offset):
Reflect changes to region::calc_offset.
(region::calc_offset):
Compute the symbolic offset if the offset is not concrete.
(region::get_relative_symbolic_offset): New function to return the
symbolic offset in bytes relative to its parent.
(field_region::get_relative_symbolic_offset): Likewise.
(element_region::get_relative_symbolic_offset): Likewise.
(offset_region::get_relative_symbolic_offset): Likewise.
(bit_range_region::get_relative_symbolic_offset): Likewise.
* region.h: Add get_relative_symbolic_offset.
* store.cc (binding_key::make):
Reflect changes to region::calc_offset.
(binding_map::apply_ctor_val_to_range): Likewise.
(binding_map::apply_ctor_pair_to_child_region): Likewise.
(binding_cluster::bind_compound_sval): Likewise.
(binding_cluster::get_any_binding): Likewise.
(binding_cluster::maybe_get_compound_binding): Likewise.
gcc/ChangeLog:
PR analyzer/106625
* doc/invoke.texi:
State that the checker also reasons about symbolic values.
gcc/testsuite/ChangeLog:
PR analyzer/106625
* gcc.dg/analyzer/data-model-1.c: Change expected result.
* gcc.dg/analyzer/out-of-bounds-5.c: New test.
* gcc.dg/analyzer/out-of-bounds-realloc-grow.c: New test.
* gcc.dg/analyzer/symbolic-gt-1.c: New test.
Diff:
---
gcc/analyzer/analyzer.h | 23 +-
gcc/analyzer/region-model-impl-calls.cc | 39 +-
gcc/analyzer/region-model.cc | 469 +++++++++++++++++++--
gcc/analyzer/region-model.h | 9 +
gcc/analyzer/region.cc | 131 +++++-
gcc/analyzer/region.h | 17 +-
gcc/analyzer/store.cc | 18 +-
gcc/doc/invoke.texi | 8 +-
gcc/testsuite/gcc.dg/analyzer/data-model-1.c | 3 +-
gcc/testsuite/gcc.dg/analyzer/out-of-bounds-5.c | 156 +++++++
.../gcc.dg/analyzer/out-of-bounds-realloc-grow.c | 87 ++++
gcc/testsuite/gcc.dg/analyzer/symbolic-gt-1.c | 76 ++++
12 files changed, 941 insertions(+), 95 deletions(-)
diff --git a/gcc/analyzer/analyzer.h b/gcc/analyzer/analyzer.h
index dcefc13a546..e4dd6d6339d 100644
--- a/gcc/analyzer/analyzer.h
+++ b/gcc/analyzer/analyzer.h
@@ -172,16 +172,17 @@ public:
static region_offset make_concrete (const region *base_region,
bit_offset_t offset)
{
- return region_offset (base_region, offset, false);
+ return region_offset (base_region, offset, NULL);
}
- static region_offset make_symbolic (const region *base_region)
+ static region_offset make_symbolic (const region *base_region,
+ const svalue *sym_offset)
{
- return region_offset (base_region, 0, true);
+ return region_offset (base_region, 0, sym_offset);
}
const region *get_base_region () const { return m_base_region; }
- bool symbolic_p () const { return m_is_symbolic; }
+ bool symbolic_p () const { return m_sym_offset != NULL; }
bit_offset_t get_bit_offset () const
{
@@ -189,22 +190,28 @@ public:
return m_offset;
}
+ const svalue *get_symbolic_byte_offset () const
+ {
+ gcc_assert (symbolic_p ());
+ return m_sym_offset;
+ }
+
bool operator== (const region_offset &other) const
{
return (m_base_region == other.m_base_region
&& m_offset == other.m_offset
- && m_is_symbolic == other.m_is_symbolic);
+ && m_sym_offset == other.m_sym_offset);
}
private:
region_offset (const region *base_region, bit_offset_t offset,
- bool is_symbolic)
- : m_base_region (base_region), m_offset (offset), m_is_symbolic (is_symbolic)
+ const svalue *sym_offset)
+ : m_base_region (base_region), m_offset (offset), m_sym_offset (sym_offset)
{}
const region *m_base_region;
bit_offset_t m_offset;
- bool m_is_symbolic;
+ const svalue *m_sym_offset;
};
extern location_t get_stmt_location (const gimple *stmt, function *fun);
diff --git a/gcc/analyzer/region-model-impl-calls.cc b/gcc/analyzer/region-model-impl-calls.cc
index 3790eaf2d79..617491be306 100644
--- a/gcc/analyzer/region-model-impl-calls.cc
+++ b/gcc/analyzer/region-model-impl-calls.cc
@@ -850,7 +850,7 @@ region_model::impl_call_realloc (const call_details &cd)
if (old_size_sval)
{
const svalue *copied_size_sval
- = get_copied_size (old_size_sval, new_size_sval);
+ = get_copied_size (model, old_size_sval, new_size_sval);
const region *copied_old_reg
= model->m_mgr->get_sized_region (freed_reg, NULL,
copied_size_sval);
@@ -896,35 +896,22 @@ region_model::impl_call_realloc (const call_details &cd)
private:
/* Return the lesser of OLD_SIZE_SVAL and NEW_SIZE_SVAL.
- If either one is symbolic, the symbolic svalue is returned. */
- const svalue *get_copied_size (const svalue *old_size_sval,
+ If unknown, OLD_SIZE_SVAL is returned. */
+ const svalue *get_copied_size (region_model *model,
+ const svalue *old_size_sval,
const svalue *new_size_sval) const
{
- tree old_size_cst = old_size_sval->maybe_get_constant ();
- tree new_size_cst = new_size_sval->maybe_get_constant ();
-
- if (old_size_cst && new_size_cst)
- {
- /* Both are constants and comparable. */
- tree cmp = fold_binary (LT_EXPR, boolean_type_node,
- old_size_cst, new_size_cst);
-
- if (cmp == boolean_true_node)
- return old_size_sval;
- else
- return new_size_sval;
- }
- else if (new_size_cst)
+ tristate res
+ = model->eval_condition (old_size_sval, GT_EXPR, new_size_sval);
+ switch (res.get_value ())
{
- /* OLD_SIZE_SVAL is symbolic, so return that. */
- return old_size_sval;
- }
- else
- {
- /* NEW_SIZE_SVAL is symbolic or both are symbolic.
- Return NEW_SIZE_SVAL, because implementations of realloc
- probably only moves the buffer if the new size is larger. */
+ case tristate::TS_TRUE:
return new_size_sval;
+ case tristate::TS_FALSE:
+ case tristate::TS_UNKNOWN:
+ return old_size_sval;
+ default:
+ gcc_unreachable ();
}
}
};
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index e84087abc1f..d321e5b6479 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -1268,7 +1268,7 @@ region_model::on_stmt_pre (const gimple *stmt,
}
}
-/* Abstract base class for all out-of-bounds warnings. */
+/* Abstract base class for all out-of-bounds warnings with concrete values. */
class out_of_bounds : public pending_diagnostic_subclass<out_of_bounds>
{
@@ -1591,49 +1591,285 @@ public:
}
};
+/* Abstract class to complain about out-of-bounds read/writes where
+ the values are symbolic. */
+
+class symbolic_past_the_end
+ : public pending_diagnostic_subclass<symbolic_past_the_end>
+{
+public:
+ symbolic_past_the_end (const region *reg, tree diag_arg, tree offset,
+ tree num_bytes, tree capacity)
+ : m_reg (reg), m_diag_arg (diag_arg), m_offset (offset),
+ m_num_bytes (num_bytes), m_capacity (capacity)
+ {}
+
+ const char *get_kind () const final override
+ {
+ return "symbolic_past_the_end";
+ }
+
+ bool operator== (const symbolic_past_the_end &other) const
+ {
+ return m_reg == other.m_reg
+ && pending_diagnostic::same_tree_p (m_diag_arg, other.m_diag_arg)
+ && pending_diagnostic::same_tree_p (m_offset, other.m_offset)
+ && pending_diagnostic::same_tree_p (m_num_bytes, other.m_num_bytes)
+ && pending_diagnostic::same_tree_p (m_capacity, other.m_capacity);
+ }
+
+ int get_controlling_option () const final override
+ {
+ return OPT_Wanalyzer_out_of_bounds;
+ }
+
+ void mark_interesting_stuff (interesting_t *interest) final override
+ {
+ interest->add_region_creation (m_reg);
+ }
+
+ label_text
+ describe_region_creation_event (const evdesc::region_creation &ev) final
+ override
+ {
+ if (m_capacity)
+ return ev.formatted_print ("capacity is %qE bytes", m_capacity);
+
+ return label_text ();
+ }
+
+ label_text
+ describe_final_event (const evdesc::final_event &ev) final override
+ {
+ const char *byte_str;
+ if (pending_diagnostic::same_tree_p (m_num_bytes, integer_one_node))
+ byte_str = "byte";
+ else
+ byte_str = "bytes";
+
+ if (m_offset)
+ {
+ if (m_num_bytes && TREE_CODE (m_num_bytes) == INTEGER_CST)
+ {
+ if (m_diag_arg)
+ return ev.formatted_print ("%s of %E %s at offset %qE"
+ " exceeds %qE", m_dir_str,
+ m_num_bytes, byte_str,
+ m_offset, m_diag_arg);
+ else
+ return ev.formatted_print ("%s of %E %s at offset %qE"
+ " exceeds the buffer", m_dir_str,
+ m_num_bytes, byte_str, m_offset);
+ }
+ else if (m_num_bytes)
+ {
+ if (m_diag_arg)
+ return ev.formatted_print ("%s of %qE %s at offset %qE"
+ " exceeds %qE", m_dir_str,
+ m_num_bytes, byte_str,
+ m_offset, m_diag_arg);
+ else
+ return ev.formatted_print ("%s of %qE %s at offset %qE"
+ " exceeds the buffer", m_dir_str,
+ m_num_bytes, byte_str, m_offset);
+ }
+ else
+ {
+ if (m_diag_arg)
+ return ev.formatted_print ("%s at offset %qE exceeds %qE",
+ m_dir_str, m_offset, m_diag_arg);
+ else
+ return ev.formatted_print ("%s at offset %qE exceeds the"
+ " buffer", m_dir_str, m_offset);
+ }
+ }
+ if (m_diag_arg)
+ return ev.formatted_print ("out-of-bounds %s on %qE",
+ m_dir_str, m_diag_arg);
+ return ev.formatted_print ("out-of-bounds %s", m_dir_str);
+ }
+
+protected:
+ const region *m_reg;
+ tree m_diag_arg;
+ tree m_offset;
+ tree m_num_bytes;
+ tree m_capacity;
+ const char *m_dir_str;
+};
+
+/* Concrete subclass to complain about overflows with symbolic values. */
+
+class symbolic_buffer_overflow : public symbolic_past_the_end
+{
+public:
+ symbolic_buffer_overflow (const region *reg, tree diag_arg, tree offset,
+ tree num_bytes, tree capacity)
+ : symbolic_past_the_end (reg, diag_arg, offset, num_bytes, capacity)
+ {
+ m_dir_str = "write";
+ }
+
+ bool emit (rich_location *rich_loc) final override
+ {
+ diagnostic_metadata m;
+ switch (m_reg->get_memory_space ())
+ {
+ default:
+ m.add_cwe (787);
+ return warning_meta (rich_loc, m, get_controlling_option (),
+ "buffer overflow");
+ case MEMSPACE_STACK:
+ m.add_cwe (121);
+ return warning_meta (rich_loc, m, get_controlling_option (),
+ "stack-based buffer overflow");
+ case MEMSPACE_HEAP:
+ m.add_cwe (122);
+ return warning_meta (rich_loc, m, get_controlling_option (),
+ "heap-based buffer overflow");
+ }
+ }
+};
+
+/* Concrete subclass to complain about overreads with symbolic values. */
+
+class symbolic_buffer_overread : public symbolic_past_the_end
+{
+public:
+ symbolic_buffer_overread (const region *reg, tree diag_arg, tree offset,
+ tree num_bytes, tree capacity)
+ : symbolic_past_the_end (reg, diag_arg, offset, num_bytes, capacity)
+ {
+ m_dir_str = "read";
+ }
+
+ bool emit (rich_location *rich_loc) final override
+ {
+ diagnostic_metadata m;
+ m.add_cwe (126);
+ return warning_meta (rich_loc, m, get_controlling_option (),
+ "buffer overread");
+ }
+};
+
+/* Check whether an access is past the end of the BASE_REG. */
+
+void region_model::check_symbolic_bounds (const region *base_reg,
+ const svalue *sym_byte_offset,
+ const svalue *num_bytes_sval,
+ const svalue *capacity,
+ enum access_direction dir,
+ region_model_context *ctxt) const
+{
+ gcc_assert (ctxt);
+
+ const svalue *next_byte
+ = m_mgr->get_or_create_binop (num_bytes_sval->get_type (), PLUS_EXPR,
+ sym_byte_offset, num_bytes_sval);
+
+ if (eval_condition_without_cm (next_byte, GT_EXPR, capacity).is_true ())
+ {
+ tree diag_arg = get_representative_tree (base_reg);
+ tree offset_tree = get_representative_tree (sym_byte_offset);
+ tree num_bytes_tree = get_representative_tree (num_bytes_sval);
+ tree capacity_tree = get_representative_tree (capacity);
+ switch (dir)
+ {
+ default:
+ gcc_unreachable ();
+ break;
+ case DIR_READ:
+ ctxt->warn (new symbolic_buffer_overread (base_reg, diag_arg,
+ offset_tree,
+ num_bytes_tree,
+ capacity_tree));
+ break;
+ case DIR_WRITE:
+ ctxt->warn (new symbolic_buffer_overflow (base_reg, diag_arg,
+ offset_tree,
+ num_bytes_tree,
+ capacity_tree));
+ break;
+ }
+ }
+}
+
+static tree
+maybe_get_integer_cst_tree (const svalue *sval)
+{
+ tree cst_tree = sval->maybe_get_constant ();
+ if (cst_tree && TREE_CODE (cst_tree) == INTEGER_CST)
+ return cst_tree;
+
+ return NULL_TREE;
+}
+
/* May complain when the access on REG is out-of-bounds. */
-void region_model::check_region_bounds (const region *reg,
- enum access_direction dir,
- region_model_context *ctxt) const
+void
+region_model::check_region_bounds (const region *reg,
+ enum access_direction dir,
+ region_model_context *ctxt) const
{
gcc_assert (ctxt);
- region_offset reg_offset = reg->get_offset ();
+ /* Get the offset. */
+ region_offset reg_offset = reg->get_offset (m_mgr);
const region *base_reg = reg_offset.get_base_region ();
- /* Bail out on symbolic offsets or symbolic regions.
+ /* Bail out on symbolic regions.
(e.g. because the analyzer did not see previous offsets on the latter,
it might think that a negative access is before the buffer). */
- if (reg_offset.symbolic_p () || base_reg->symbolic_p ())
+ if (base_reg->symbolic_p ())
return;
- byte_offset_t offset_unsigned
- = reg_offset.get_bit_offset () >> LOG2_BITS_PER_UNIT;
+
+ /* Find out how many bytes were accessed. */
+ const svalue *num_bytes_sval = reg->get_byte_size_sval (m_mgr);
+ tree num_bytes_tree = maybe_get_integer_cst_tree (num_bytes_sval);
+
+ /* Get the capacity of the buffer. */
+ const svalue *capacity = get_capacity (base_reg);
+ tree cst_capacity_tree = maybe_get_integer_cst_tree (capacity);
+
/* The constant offset from a pointer is represented internally as a sizetype
but should be interpreted as a signed value here. The statement below
- converts the offset to a signed integer with the same precision the
- sizetype has on the target system.
+ converts the offset from bits to bytes and then to a signed integer with
+ the same precision the sizetype has on the target system.
For example, this is needed for out-of-bounds-3.c test1 to pass when
compiled with a 64-bit gcc build targeting 32-bit systems. */
- byte_offset_t offset
- = offset_unsigned.to_shwi (TYPE_PRECISION (size_type_node));
-
- /* Find out how many bytes were accessed. */
- const svalue *num_bytes_sval = reg->get_byte_size_sval (m_mgr);
- tree num_bytes_tree = num_bytes_sval->maybe_get_constant ();
- if (!num_bytes_tree || TREE_CODE (num_bytes_tree) != INTEGER_CST)
- /* If we do not know how many bytes were read/written,
- assume that at least one byte was read/written. */
- num_bytes_tree = integer_one_node;
+ byte_offset_t offset;
+ if (!reg_offset.symbolic_p ())
+ offset = wi::sext (reg_offset.get_bit_offset () >> LOG2_BITS_PER_UNIT,
+ TYPE_PRECISION (size_type_node));
+
+ /* If either the offset or the number of bytes accessed are symbolic,
+ we have to reason about symbolic values. */
+ if (reg_offset.symbolic_p () || !num_bytes_tree)
+ {
+ const svalue* byte_offset_sval;
+ if (!reg_offset.symbolic_p ())
+ {
+ tree offset_tree = wide_int_to_tree (integer_type_node, offset);
+ byte_offset_sval
+ = m_mgr->get_or_create_constant_svalue (offset_tree);
+ }
+ else
+ byte_offset_sval = reg_offset.get_symbolic_byte_offset ();
+ check_symbolic_bounds (base_reg, byte_offset_sval, num_bytes_sval,
+ capacity, dir, ctxt);
+ return;
+ }
+ /* Otherwise continue to check with concrete values. */
byte_range out (0, 0);
/* NUM_BYTES_TREE should always be interpreted as unsigned. */
- byte_range read_bytes (offset, wi::to_offset (num_bytes_tree).to_uhwi ());
+ byte_offset_t num_bytes_unsigned = wi::to_offset (num_bytes_tree);
+ byte_range read_bytes (offset, num_bytes_unsigned);
/* If read_bytes has a subset < 0, we do have an underflow. */
if (read_bytes.falls_short_of_p (0, &out))
{
- tree diag_arg = get_representative_tree (reg->get_base_region ());
+ tree diag_arg = get_representative_tree (base_reg);
switch (dir)
{
default:
@@ -1648,9 +1884,10 @@ void region_model::check_region_bounds (const region *reg,
}
}
- const svalue *capacity = get_capacity (base_reg);
- tree cst_capacity_tree = capacity->maybe_get_constant ();
- if (!cst_capacity_tree || TREE_CODE (cst_capacity_tree) != INTEGER_CST)
+ /* For accesses past the end, we do need a concrete capacity. No need to
+ do a symbolic check here because the inequality check does not reason
+ whether constants are greater than symbolic values. */
+ if (!cst_capacity_tree)
return;
byte_range buffer (0, wi::to_offset (cst_capacity_tree));
@@ -1659,7 +1896,7 @@ void region_model::check_region_bounds (const region *reg,
{
tree byte_bound = wide_int_to_tree (size_type_node,
buffer.get_next_byte_offset ());
- tree diag_arg = get_representative_tree (reg->get_base_region ());
+ tree diag_arg = get_representative_tree (base_reg);
switch (dir)
{
@@ -3907,6 +4144,49 @@ region_model::eval_condition_without_cm (const svalue *lhs,
return res;
}
+ /* Handle comparisons between two svalues with more than one operand. */
+ if (const binop_svalue *binop = lhs->dyn_cast_binop_svalue ())
+ {
+ switch (op)
+ {
+ default:
+ break;
+ case EQ_EXPR:
+ {
+ /* TODO: binops can be equal even if they are not structurally
+ equal in case of commutative operators. */
+ tristate res = structural_equality (lhs, rhs);
+ if (res.is_true ())
+ return res;
+ }
+ break;
+ case LE_EXPR:
+ {
+ tristate res = structural_equality (lhs, rhs);
+ if (res.is_true ())
+ return res;
+ }
+ break;
+ case GE_EXPR:
+ {
+ tristate res = structural_equality (lhs, rhs);
+ if (res.is_true ())
+ return res;
+ res = symbolic_greater_than (binop, rhs);
+ if (res.is_true ())
+ return res;
+ }
+ break;
+ case GT_EXPR:
+ {
+ tristate res = symbolic_greater_than (binop, rhs);
+ if (res.is_true ())
+ return res;
+ }
+ break;
+ }
+ }
+
return tristate::TS_UNKNOWN;
}
@@ -3928,6 +4208,123 @@ region_model::compare_initial_and_pointer (const initial_svalue *init,
return tristate::TS_UNKNOWN;
}
+/* Return true if SVAL is definitely positive. */
+
+static bool
+is_positive_svalue (const svalue *sval)
+{
+ if (tree cst = sval->maybe_get_constant ())
+ return !zerop (cst) && get_range_pos_neg (cst) == 1;
+ tree type = sval->get_type ();
+ if (!type)
+ return false;
+ /* Consider a binary operation size_t + int. The analyzer wraps the int in
+ an unaryop_svalue, converting it to a size_t, but in the dynamic execution
+ the result is smaller than the first operand. Thus, we have to look if
+ the argument of the unaryop_svalue is also positive. */
+ if (const unaryop_svalue *un_op = dyn_cast <const unaryop_svalue *> (sval))
+ return CONVERT_EXPR_CODE_P (un_op->get_op ()) && TYPE_UNSIGNED (type)
+ && is_positive_svalue (un_op->get_arg ());
+ return TYPE_UNSIGNED (type);
+}
+
+/* Return true if A is definitely larger than B.
+
+ Limitation: does not account for integer overflows and does not try to
+ return false, so it can not be used negated. */
+
+tristate
+region_model::symbolic_greater_than (const binop_svalue *bin_a,
+ const svalue *b) const
+{
+ if (bin_a->get_op () == PLUS_EXPR || bin_a->get_op () == MULT_EXPR)
+ {
+ /* Eliminate the right-hand side of both svalues. */
+ if (const binop_svalue *bin_b = dyn_cast <const binop_svalue *> (b))
+ if (bin_a->get_op () == bin_b->get_op ()
+ && eval_condition_without_cm (bin_a->get_arg1 (),
+ GT_EXPR,
+ bin_b->get_arg1 ()).is_true ()
+ && eval_condition_without_cm (bin_a->get_arg0 (),
+ GE_EXPR,
+ bin_b->get_arg0 ()).is_true ())
+ return tristate (tristate::TS_TRUE);
+
+ /* Otherwise, try to remove a positive offset or factor from BIN_A. */
+ if (is_positive_svalue (bin_a->get_arg1 ())
+ && eval_condition_without_cm (bin_a->get_arg0 (),
+ GE_EXPR, b).is_true ())
+ return tristate (tristate::TS_TRUE);
+ }
+ return tristate::unknown ();
+}
+
+/* Return true if A and B are equal structurally.
+
+ Structural equality means that A and B are equal if the svalues A and B have
+ the same nodes at the same positions in the tree and the leafs are equal.
+ Equality for conjured_svalues and initial_svalues is determined by comparing
+ the pointers while constants are compared by value. That behavior is useful
+ to check for binaryop_svlaues that evaluate to the same concrete value but
+ might use one operand with a different type but the same constant value.
+
+ For example,
+ binop_svalue (mult_expr,
+ initial_svalue (‘size_t’, decl_region (..., 'some_var')),
+ constant_svalue (‘size_t’, 4))
+ and
+ binop_svalue (mult_expr,
+ initial_svalue (‘size_t’, decl_region (..., 'some_var'),
+ constant_svalue (‘sizetype’, 4))
+ are structurally equal. A concrete C code example, where this occurs, can
+ be found in test7 of out-of-bounds-5.c. */
+
+tristate
+region_model::structural_equality (const svalue *a, const svalue *b) const
+{
+ /* If A and B are referentially equal, they are also structurally equal. */
+ if (a == b)
+ return tristate (tristate::TS_TRUE);
+
+ switch (a->get_kind ())
+ {
+ default:
+ return tristate::unknown ();
+ /* SK_CONJURED and SK_INITIAL are already handled
+ by the referential equality above. */
+ case SK_CONSTANT:
+ {
+ tree a_cst = a->maybe_get_constant ();
+ tree b_cst = b->maybe_get_constant ();
+ if (a_cst && b_cst)
+ return tristate (tree_int_cst_equal (a_cst, b_cst));
+ }
+ return tristate (tristate::TS_FALSE);
+ case SK_UNARYOP:
+ {
+ const unaryop_svalue *un_a = as_a <const unaryop_svalue *> (a);
+ if (const unaryop_svalue *un_b = dyn_cast <const unaryop_svalue *> (b))
+ return tristate (pending_diagnostic::same_tree_p (un_a->get_type (),
+ un_b->get_type ())
+ && un_a->get_op () == un_b->get_op ()
+ && structural_equality (un_a->get_arg (),
+ un_b->get_arg ()));
+ }
+ return tristate (tristate::TS_FALSE);
+ case SK_BINOP:
+ {
+ const binop_svalue *bin_a = as_a <const binop_svalue *> (a);
+ if (const binop_svalue *bin_b = dyn_cast <const binop_svalue *> (b))
+ return tristate (bin_a->get_op () == bin_b->get_op ()
+ && structural_equality (bin_a->get_arg0 (),
+ bin_b->get_arg0 ())
+ && structural_equality (bin_a->get_arg1 (),
+ bin_b->get_arg1 ()));
+ }
+ return tristate (tristate::TS_FALSE);
+ }
+}
+
/* Handle various constraints of the form:
LHS: ((bool)INNER_LHS INNER_OP INNER_RHS))
OP : == or !=
@@ -5637,7 +6034,7 @@ test_struct ()
/* Verify get_offset for "c.x". */
{
const region *c_x_reg = model.get_lvalue (c_x, NULL);
- region_offset offset = c_x_reg->get_offset ();
+ region_offset offset = c_x_reg->get_offset (&mgr);
ASSERT_EQ (offset.get_base_region (), model.get_lvalue (c, NULL));
ASSERT_EQ (offset.get_bit_offset (), 0);
}
@@ -5645,7 +6042,7 @@ test_struct ()
/* Verify get_offset for "c.y". */
{
const region *c_y_reg = model.get_lvalue (c_y, NULL);
- region_offset offset = c_y_reg->get_offset ();
+ region_offset offset = c_y_reg->get_offset (&mgr);
ASSERT_EQ (offset.get_base_region (), model.get_lvalue (c, NULL));
ASSERT_EQ (offset.get_bit_offset (), INT_TYPE_SIZE);
}
@@ -7140,7 +7537,7 @@ test_var ()
/* Verify get_offset for "i". */
{
- region_offset offset = i_reg->get_offset ();
+ region_offset offset = i_reg->get_offset (&mgr);
ASSERT_EQ (offset.get_base_region (), i_reg);
ASSERT_EQ (offset.get_bit_offset (), 0);
}
@@ -7189,7 +7586,7 @@ test_array_2 ()
/* Verify get_offset for "arr[0]". */
{
const region *arr_0_reg = model.get_lvalue (arr_0, NULL);
- region_offset offset = arr_0_reg->get_offset ();
+ region_offset offset = arr_0_reg->get_offset (&mgr);
ASSERT_EQ (offset.get_base_region (), model.get_lvalue (arr, NULL));
ASSERT_EQ (offset.get_bit_offset (), 0);
}
@@ -7197,11 +7594,19 @@ test_array_2 ()
/* Verify get_offset for "arr[1]". */
{
const region *arr_1_reg = model.get_lvalue (arr_1, NULL);
- region_offset offset = arr_1_reg->get_offset ();
+ region_offset offset = arr_1_reg->get_offset (&mgr);
ASSERT_EQ (offset.get_base_region (), model.get_lvalue (arr, NULL));
ASSERT_EQ (offset.get_bit_offset (), INT_TYPE_SIZE);
}
+ /* Verify get_offset for "arr[i]". */
+ {
+ const region *arr_i_reg = model.get_lvalue (arr_i, NULL);
+ region_offset offset = arr_i_reg->get_offset (&mgr);
+ ASSERT_EQ (offset.get_base_region (), model.get_lvalue (arr, NULL));
+ ASSERT_EQ (offset.get_symbolic_byte_offset ()->get_kind (), SK_BINOP);
+ }
+
/* "arr[i] = i;" - this should remove the earlier bindings. */
model.set_value (arr_i, i, NULL);
ASSERT_EQ (model.get_rvalue (arr_i, NULL), model.get_rvalue (i, NULL));
diff --git a/gcc/analyzer/region-model.h b/gcc/analyzer/region-model.h
index a1f2165e145..977cccf0ef7 100644
--- a/gcc/analyzer/region-model.h
+++ b/gcc/analyzer/region-model.h
@@ -717,6 +717,9 @@ class region_model
const svalue *rhs) const;
tristate compare_initial_and_pointer (const initial_svalue *init,
const region_svalue *ptr) const;
+ tristate symbolic_greater_than (const binop_svalue *a,
+ const svalue *b) const;
+ tristate structural_equality (const svalue *a, const svalue *b) const;
tristate eval_condition (tree lhs,
enum tree_code op,
tree rhs,
@@ -874,6 +877,12 @@ class region_model
region_model_context *ctxt) const;
void check_region_size (const region *lhs_reg, const svalue *rhs_sval,
region_model_context *ctxt) const;
+ void check_symbolic_bounds (const region *base_reg,
+ const svalue *sym_byte_offset,
+ const svalue *num_bytes_sval,
+ const svalue *capacity,
+ enum access_direction dir,
+ region_model_context *ctxt) const;
void check_region_bounds (const region *reg, enum access_direction dir,
region_model_context *ctxt) const;
diff --git a/gcc/analyzer/region.cc b/gcc/analyzer/region.cc
index 9c8279b130d..09646bfc98a 100644
--- a/gcc/analyzer/region.cc
+++ b/gcc/analyzer/region.cc
@@ -290,10 +290,10 @@ region::maybe_get_decl () const
first call and caching it internally). */
region_offset
-region::get_offset () const
+region::get_offset (region_model_manager *mgr) const
{
if(!m_cached_offset)
- m_cached_offset = new region_offset (calc_offset ());
+ m_cached_offset = new region_offset (calc_offset (mgr));
return *m_cached_offset;
}
@@ -491,10 +491,11 @@ region::get_subregions_for_binding (region_model_manager *mgr,
or a symbolic offset. */
region_offset
-region::calc_offset () const
+region::calc_offset (region_model_manager *mgr) const
{
const region *iter_region = this;
bit_offset_t accum_bit_offset = 0;
+ const svalue *accum_byte_sval = NULL;
while (iter_region)
{
@@ -504,16 +505,36 @@ region::calc_offset () const
case RK_ELEMENT:
case RK_OFFSET:
case RK_BIT_RANGE:
- {
- bit_offset_t rel_bit_offset;
- if (!iter_region->get_relative_concrete_offset (&rel_bit_offset))
- return region_offset::make_symbolic
- (iter_region->get_parent_region ());
- accum_bit_offset += rel_bit_offset;
- iter_region = iter_region->get_parent_region ();
- }
+ if (accum_byte_sval)
+ {
+ const svalue *sval
+ = iter_region->get_relative_symbolic_offset (mgr);
+ accum_byte_sval
+ = mgr->get_or_create_binop (sval->get_type (), PLUS_EXPR,
+ accum_byte_sval, sval);
+ iter_region = iter_region->get_parent_region ();
+ }
+ else
+ {
+ bit_offset_t rel_bit_offset;
+ if (iter_region->get_relative_concrete_offset (&rel_bit_offset))
+ {
+ accum_bit_offset += rel_bit_offset;
+ iter_region = iter_region->get_parent_region ();
+ }
+ else
+ {
+ /* If the iter_region is not concrete anymore, convert the
+ accumulated bits to a svalue in bytes and revisit the
+ iter_region collecting the symbolic value. */
+ byte_offset_t byte_offset = accum_bit_offset / BITS_PER_UNIT;
+ tree offset_tree = wide_int_to_tree (integer_type_node,
+ byte_offset);
+ accum_byte_sval
+ = mgr->get_or_create_constant_svalue (offset_tree);
+ }
+ }
continue;
-
case RK_SIZED:
iter_region = iter_region->get_parent_region ();
continue;
@@ -527,10 +548,18 @@ region::calc_offset () const
continue;
default:
- return region_offset::make_concrete (iter_region, accum_bit_offset);
+ return accum_byte_sval
+ ? region_offset::make_symbolic (iter_region,
+ accum_byte_sval)
+ : region_offset::make_concrete (iter_region,
+ accum_bit_offset);
}
}
- return region_offset::make_concrete (iter_region, accum_bit_offset);
+
+ return accum_byte_sval ? region_offset::make_symbolic (iter_region,
+ accum_byte_sval)
+ : region_offset::make_concrete (iter_region,
+ accum_bit_offset);
}
/* Base implementation of region::get_relative_concrete_offset vfunc. */
@@ -541,6 +570,14 @@ region::get_relative_concrete_offset (bit_offset_t *) const
return false;
}
+/* Base implementation of region::get_relative_symbolic_offset vfunc. */
+
+const svalue *
+region::get_relative_symbolic_offset (region_model_manager *mgr) const
+{
+ return mgr->get_or_create_unknown_svalue (integer_type_node);
+}
+
/* Attempt to get the position and size of this region expressed as a
concrete range of bytes relative to its parent.
If successful, return true and write to *OUT.
@@ -1316,6 +1353,25 @@ field_region::get_relative_concrete_offset (bit_offset_t *out) const
return true;
}
+
+/* Implementation of region::get_relative_symbolic_offset vfunc
+ for field_region.
+ If known, the returned svalue is equal to the offset converted to bytes and
+ rounded off. */
+
+const svalue *
+field_region::get_relative_symbolic_offset (region_model_manager *mgr) const
+{
+ bit_offset_t out;
+ if (get_relative_concrete_offset (&out))
+ {
+ tree cst_tree
+ = wide_int_to_tree (integer_type_node, out / BITS_PER_UNIT);
+ return mgr->get_or_create_constant_svalue (cst_tree);
+ }
+ return mgr->get_or_create_unknown_svalue (integer_type_node);
+}
+
/* class element_region : public region. */
/* Implementation of region::accept vfunc for element_region. */
@@ -1382,6 +1438,29 @@ element_region::get_relative_concrete_offset (bit_offset_t *out) const
return false;
}
+/* Implementation of region::get_relative_symbolic_offset vfunc
+ for element_region. */
+
+const svalue *
+element_region::get_relative_symbolic_offset (region_model_manager *mgr) const
+{
+ tree elem_type = get_type ();
+
+ /* First, use int_size_in_bytes, to reject the case where we
+ have an incomplete type, or a non-constant value. */
+ HOST_WIDE_INT hwi_byte_size = int_size_in_bytes (elem_type);
+ if (hwi_byte_size > 0)
+ {
+ tree byte_size_tree = wide_int_to_tree (integer_type_node,
+ hwi_byte_size);
+ const svalue *byte_size_sval
+ = mgr->get_or_create_constant_svalue (byte_size_tree);
+ return mgr->get_or_create_binop (integer_type_node, MULT_EXPR,
+ m_index, byte_size_sval);
+ }
+ return mgr->get_or_create_unknown_svalue (integer_type_node);
+}
+
/* class offset_region : public region. */
/* Implementation of region::accept vfunc for offset_region. */
@@ -1438,6 +1517,16 @@ offset_region::get_relative_concrete_offset (bit_offset_t *out) const
return false;
}
+/* Implementation of region::get_relative_symbolic_offset vfunc
+ for offset_region. */
+
+const svalue *
+offset_region::get_relative_symbolic_offset (region_model_manager *mgr
+ ATTRIBUTE_UNUSED) const
+{
+ return get_byte_offset ();
+}
+
/* Implementation of region::get_byte_size_sval vfunc for offset_region. */
const svalue *
@@ -1683,6 +1772,20 @@ bit_range_region::get_relative_concrete_offset (bit_offset_t *out) const
return true;
}
+/* Implementation of region::get_relative_symbolic_offset vfunc for
+ bit_range_region.
+ The returned svalue is equal to the offset converted to bytes and
+ rounded off. */
+
+const svalue *
+bit_range_region::get_relative_symbolic_offset (region_model_manager *mgr)
+ const
+{
+ byte_offset_t start_byte = m_bits.get_start_bit_offset () / BITS_PER_UNIT;
+ tree start_bit_tree = wide_int_to_tree (integer_type_node, start_byte);
+ return mgr->get_or_create_constant_svalue (start_bit_tree);
+}
+
/* class var_arg_region : public region. */
void
diff --git a/gcc/analyzer/region.h b/gcc/analyzer/region.h
index 34ce1fa1714..6315fac62e5 100644
--- a/gcc/analyzer/region.h
+++ b/gcc/analyzer/region.h
@@ -175,7 +175,7 @@ public:
bool involves_p (const svalue *sval) const;
- region_offset get_offset () const;
+ region_offset get_offset (region_model_manager *mgr) const;
/* Attempt to get the size of this region as a concrete number of bytes.
If successful, return true and write the size to *OUT.
@@ -196,6 +196,11 @@ public:
Otherwise return false. */
virtual bool get_relative_concrete_offset (bit_offset_t *out) const;
+ /* Get the offset in bytes of this region relative to its parent as a svalue.
+ Might return an unknown_svalue. */
+ virtual const svalue *
+ get_relative_symbolic_offset (region_model_manager *mgr) const;
+
/* Attempt to get the position and size of this region expressed as a
concrete range of bytes relative to its parent.
If successful, return true and write to *OUT.
@@ -226,7 +231,7 @@ public:
region (complexity c, unsigned id, const region *parent, tree type);
private:
- region_offset calc_offset () const;
+ region_offset calc_offset (region_model_manager *mgr) const;
complexity m_complexity;
unsigned m_id; // purely for deterministic sorting at this stage, for dumps
@@ -751,6 +756,8 @@ public:
tree get_field () const { return m_field; }
bool get_relative_concrete_offset (bit_offset_t *out) const final override;
+ const svalue *get_relative_symbolic_offset (region_model_manager *mgr)
+ const final override;
private:
tree m_field;
@@ -835,6 +842,8 @@ public:
virtual bool
get_relative_concrete_offset (bit_offset_t *out) const final override;
+ const svalue *get_relative_symbolic_offset (region_model_manager *mgr)
+ const final override;
private:
const svalue *m_index;
@@ -919,6 +928,8 @@ public:
const svalue *get_byte_offset () const { return m_byte_offset; }
bool get_relative_concrete_offset (bit_offset_t *out) const final override;
+ const svalue *get_relative_symbolic_offset (region_model_manager *mgr)
+ const final override;
const svalue * get_byte_size_sval (region_model_manager *mgr)
const final override;
@@ -1245,6 +1256,8 @@ public:
bool get_bit_size (bit_size_t *out) const final override;
const svalue *get_byte_size_sval (region_model_manager *mgr) const final override;
bool get_relative_concrete_offset (bit_offset_t *out) const final override;
+ const svalue *get_relative_symbolic_offset (region_model_manager *mgr)
+ const final override;
private:
bit_range m_bits;
diff --git a/gcc/analyzer/store.cc b/gcc/analyzer/store.cc
index 848c5e1aaff..ec5232cb055 100644
--- a/gcc/analyzer/store.cc
+++ b/gcc/analyzer/store.cc
@@ -123,7 +123,7 @@ uncertainty_t::dump (bool simple) const
const binding_key *
binding_key::make (store_manager *mgr, const region *r)
{
- region_offset offset = r->get_offset ();
+ region_offset offset = r->get_offset (mgr->get_svalue_manager ());
if (offset.symbolic_p ())
return mgr->get_symbolic_binding (r);
else
@@ -897,7 +897,7 @@ binding_map::apply_ctor_val_to_range (const region *parent_reg,
= get_subregion_within_ctor (parent_reg, min_index, mgr);
const region *max_element
= get_subregion_within_ctor (parent_reg, max_index, mgr);
- region_offset min_offset = min_element->get_offset ();
+ region_offset min_offset = min_element->get_offset (mgr);
if (min_offset.symbolic_p ())
return false;
bit_offset_t start_bit_offset = min_offset.get_bit_offset ();
@@ -955,11 +955,11 @@ binding_map::apply_ctor_pair_to_child_region (const region *parent_reg,
gcc_assert (sval_byte_size != -1);
bit_size_t sval_bit_size = sval_byte_size * BITS_PER_UNIT;
/* Get offset of child relative to base region. */
- region_offset child_base_offset = child_reg->get_offset ();
+ region_offset child_base_offset = child_reg->get_offset (mgr);
if (child_base_offset.symbolic_p ())
return false;
/* Convert to an offset relative to the parent region. */
- region_offset parent_base_offset = parent_reg->get_offset ();
+ region_offset parent_base_offset = parent_reg->get_offset (mgr);
gcc_assert (!parent_base_offset.symbolic_p ());
bit_offset_t child_parent_offset
= (child_base_offset.get_bit_offset ()
@@ -1365,7 +1365,8 @@ binding_cluster::bind_compound_sval (store_manager *mgr,
const region *reg,
const compound_svalue *compound_sval)
{
- region_offset reg_offset = reg->get_offset ();
+ region_offset reg_offset
+ = reg->get_offset (mgr->get_svalue_manager ());
if (reg_offset.symbolic_p ())
{
m_touched = true;
@@ -1614,7 +1615,7 @@ binding_cluster::get_any_binding (store_manager *mgr,
/* Alternatively, if this is a symbolic read and the cluster has any bindings,
then we don't know if we're reading those values or not, so the result
is also "UNKNOWN". */
- if (reg->get_offset ().symbolic_p ()
+ if (reg->get_offset (mgr->get_svalue_manager ()).symbolic_p ()
&& m_map.elements () > 0)
{
region_model_manager *rmm_mgr = mgr->get_svalue_manager ();
@@ -1643,10 +1644,11 @@ const svalue *
binding_cluster::maybe_get_compound_binding (store_manager *mgr,
const region *reg) const
{
- region_offset cluster_offset = m_base_region->get_offset ();
+ region_offset cluster_offset
+ = m_base_region->get_offset (mgr->get_svalue_manager ());
if (cluster_offset.symbolic_p ())
return NULL;
- region_offset reg_offset = reg->get_offset ();
+ region_offset reg_offset = reg->get_offset (mgr->get_svalue_manager ());
if (reg_offset.symbolic_p ())
return NULL;
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index cc631dfa261..5c066219a7d 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10051,9 +10051,11 @@ This warning requires @option{-fanalyzer} to enable it; use
@option{-Wno-analyzer-out-of-bounds} to disable it.
This diagnostic warns for path through the code in which a buffer is
-definitely read or written out-of-bounds. The diagnostic only applies
-for cases where the analyzer is able to determine a constant offset and
-for accesses past the end of a buffer, also a constant capacity.
+definitely read or written out-of-bounds. The diagnostic applies for
+cases where the analyzer is able to determine a constant offset and for
+accesses past the end of a buffer, also a constant capacity. Further,
+the diagnostic does limited checking for accesses past the end when the
+offset as well as the capacity is symbolic.
See @uref{https://cwe.mitre.org/data/definitions/119.html, CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer}.
diff --git a/gcc/testsuite/gcc.dg/analyzer/data-model-1.c b/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
index 43181911795..d8930d189bb 100644
--- a/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
+++ b/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
@@ -624,8 +624,7 @@ void test_29a (struct coord p[])
__analyzer_eval (q[-2].y == 107025); /* { dg-warning "TRUE" } */
q -= 2;
- __analyzer_eval (q == &p[7]); /* { dg-warning "UNKNOWN" } */
- // TODO: make this be TRUE
+ __analyzer_eval (q == &p[7]); /* { dg-warning "TRUE" } */
__analyzer_eval (q->x == 107024); /* { dg-warning "TRUE" } */
__analyzer_eval (q->y == 107025); /* { dg-warning "TRUE" } */
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-5.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-5.c
new file mode 100644
index 00000000000..7dc0bc5bf18
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-5.c
@@ -0,0 +1,156 @@
+/* { dg-additional-options "-Wno-unused-but-set-variable" } */
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <alloca.h>
+#include <stdint.h>
+
+/* Tests with symbolic values. */
+
+void test1 (size_t size)
+{
+ char *buf = __builtin_malloc (size);
+ if (!buf) return;
+
+ buf[size] = '\0'; /* { dg-warning "overflow" } */
+ free (buf);
+}
+
+void test2 (size_t size)
+{
+ char *buf = __builtin_malloc (size);
+ if (!buf) return;
+
+ buf[size + 1] = '\0'; /* { dg-warning "overflow" } */
+ free (buf);
+}
+
+void test3 (size_t size, size_t op)
+{
+ char *buf = __builtin_malloc (size);
+ if (!buf) return;
+
+ buf[size + op] = '\0'; /* { dg-warning "overflow" } */
+ free (buf);
+}
+
+void test4 (size_t size, unsigned short s)
+{
+ char *buf = __builtin_alloca (size);
+ buf[size + s] = '\0'; /* { dg-warning "overflow" } */
+}
+
+void test5 (size_t size)
+{
+ int32_t *buf = __builtin_alloca (4 * size);
+ buf[size] = 42; /* { dg-warning "overflow" } */
+}
+
+void test6 (size_t size)
+{
+ int32_t *buf = __builtin_alloca (4 * size);
+ memset (buf, 0, 4 * size);
+ int32_t last = *(buf + 4 * size); /* { dg-warning "overread" } */
+}
+
+void test7 (size_t size)
+{
+ int32_t *buf = __builtin_alloca (4 * size + 3); /* { dg-warning "allocated buffer size is not a multiple of the pointee's size" } */
+ buf[size] = 42; /* { dg-warning "overflow" } */
+}
+
+/* Test where the offset itself is not out-of-bounds
+ but multiple bytes are read. */
+
+void test8 (size_t size, size_t offset)
+{
+ char src[size];
+ char dst[size];
+ memcpy (dst, src, size + offset); /* { dg-line test8 } */
+ /* { dg-warning "overread" "warning" { target *-*-* } test8 } */
+ /* { dg-warning "overflow" "warning" { target *-*-* } test8 } */
+}
+
+void test9 (size_t size, size_t offset)
+{
+ int32_t src[size];
+ int32_t dst[size];
+ memcpy (dst, src, 4 * size + 1); /* { dg-line test9 } */
+ /* { dg-warning "overread" "warning" { target *-*-* } test9 } */
+ /* { dg-warning "overflow" "warning" { target *-*-* } test9 } */
+}
+
+/* Test for no false-positives. */
+
+void test10 (size_t size)
+{
+ int32_t buf[4 * size];
+ /* 4 * size is smaller than 4 * 4 * size. */
+ buf[size] = 42;
+}
+
+void test11 (size_t size)
+{
+ int32_t *buf = __builtin_alloca (4 * size + 5); /* { dg-warning "allocated buffer size is not a multiple of the pointee's size" } */
+ buf[size] = 42;
+}
+
+void test12 (size_t size, size_t offset)
+{
+ int buf[size];
+ buf[offset] = 42;
+}
+
+void test13 (size_t size, int offset)
+{
+ int buf[size];
+ /* We don't know whether offset is positive or not. */
+ buf[size + offset] = 42;
+}
+
+void test14 (size_t size, size_t offset, size_t offset2)
+{
+ int buf[size];
+ /* We don't know whether offset > offset2. */
+ buf[size + offset - offset2] = 42;
+}
+
+void test15 (size_t a, size_t b)
+{
+ int buf[a * b];
+ /* We can't reason about a*b < a+b either. */
+ buf[a + b] = 42;
+}
+
+/* Misc. */
+
+char *test98 (const char *x, const char *y)
+{
+ size_t len_x = __builtin_strlen (x);
+ size_t len_y = __builtin_strlen (y);
+ size_t sz = len_x + len_y + 1;
+ char *result = __builtin_malloc (sz);
+ if (!result)
+ return NULL;
+ __builtin_memcpy (result, x, len_x);
+ __builtin_memcpy (result + len_x, y, len_y);
+ result[len_x + len_y] = '\0';
+ return result;
+}
+
+char *test99 (const char *x, const char *y)
+{
+ size_t len_x = __builtin_strlen (x);
+ size_t len_y = __builtin_strlen (y);
+ /* BUG (root cause): forgot to add 1 for terminator. */
+ size_t sz = len_x + len_y;
+ char *result = __builtin_malloc (sz);
+ if (!result)
+ return NULL;
+ __builtin_memcpy (result, x, len_x);
+ __builtin_memcpy (result + len_x, y, len_y);
+ /* BUG (symptom): off-by-one out-of-bounds write to heap. */
+ result[len_x + len_y] = '\0'; /* { dg-warning "overflow" } */
+ return result;
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-realloc-grow.c b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-realloc-grow.c
new file mode 100644
index 00000000000..707611e08a6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/out-of-bounds-realloc-grow.c
@@ -0,0 +1,87 @@
+/* { dg-additional-options "-Wno-analyzer-too-complex" } */
+
+/* Reduced from gnulib/read-file.c.
+
+ Tests that there is no false-positive on
+ realloc when the buffer is growing. */
+
+#include <stdlib.h>
+
+/* Indicate that the file is treated as binary. */
+#define RF_BINARY 0x1
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+char *
+fread_file (FILE *stream, int flags, size_t *length)
+{
+ char *buf = NULL;
+ size_t alloc = BUFSIZ;
+
+ if (!(buf = malloc (alloc)))
+ return NULL; /* errno is ENOMEM. */
+
+ {
+ size_t size = 0; /* number of bytes read so far */
+ int save_errno;
+
+ for (;;)
+ {
+ /* This reads 1 more than the size of a regular file
+ so that we get eof immediately. */
+ size_t requested = alloc - size;
+ size_t count = fread (buf + size, 1, requested, stream);
+ size += count;
+
+ {
+ char *new_buf;
+
+ if (alloc < PTRDIFF_MAX - alloc / 2)
+ alloc = alloc + alloc / 2;
+ else
+ alloc = PTRDIFF_MAX;
+
+ if (!(new_buf = realloc (buf, alloc)))
+ {
+ save_errno = errno;
+ break;
+ }
+
+ buf = new_buf;
+ }
+ }
+
+ free (buf);
+ errno = save_errno;
+ return NULL;
+ }
+}
+
+/* Open and read the contents of FILENAME, and return a newly
+ allocated string with the content, and set *LENGTH to the length of
+ the string. The string is zero-terminated, but the terminating
+ zero byte is not counted in *LENGTH. On errors, *LENGTH is
+ undefined, errno preserves the values set by system functions (if
+ any), and NULL is returned.
+ If the RF_BINARY flag is set in FLAGS, the file is opened in binary
+ mode. If the RF_SENSITIVE flag is set in FLAGS, the memory buffer
+ internally allocated will be cleared upon failure. */
+char *
+read_file (const char *filename, int flags, size_t *length)
+{
+ const char *mode = (flags & RF_BINARY) ? "rbe" : "re";
+ FILE *stream = fopen (filename, mode);
+ char *out;
+
+ if (!stream)
+ return NULL;
+
+ out = fread_file (stream, flags, length);
+
+ fclose (stream);
+
+ return out;
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/symbolic-gt-1.c b/gcc/testsuite/gcc.dg/analyzer/symbolic-gt-1.c
new file mode 100644
index 00000000000..140abce6961
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/symbolic-gt-1.c
@@ -0,0 +1,76 @@
+#include <string.h>
+#include "analyzer-decls.h"
+
+/* Test GT_EXPR comparison of symbolic values. */
+
+void test1 (size_t size)
+{
+ size_t a = 4 * size + 1;
+ size_t b = 4 * size;
+ __analyzer_eval (a > b); /* { dg-warning "TRUE" } */
+}
+
+void test2 (size_t size, size_t offset)
+{
+ size_t a = size + offset;
+ size_t b = size;
+ __analyzer_eval (a > b); /* { dg-warning "TRUE" } */
+}
+
+void test3 (size_t size, size_t offset)
+{
+ size_t a = size * offset;
+ size_t b = size;
+ __analyzer_eval (a > b); /* { dg-warning "TRUE" } */
+}
+
+void test4 (size_t size)
+{
+ size_t op = -1;
+ size_t a = size + op;
+ size_t b = size;
+ __analyzer_eval (a > b); /* { dg-warning "UNKNOWN" } */
+}
+
+void test5 (size_t size)
+{
+ size_t a = size - 1;
+ size_t b = size;
+ __analyzer_eval (a > b); /* { dg-warning "UNKNOWN" } */
+}
+
+void test6 (size_t size, int offset)
+{
+ /* OFFSET is a symbolic integer, thus could be negative. */
+ size_t a = size + offset;
+ size_t b = size;
+ __analyzer_eval (a > b); /* { dg-warning "UNKNOWN" } */
+}
+
+void test7 (size_t size, size_t mul)
+{
+ size_t a = mul * size + 1;
+ size_t b = mul * size;
+ __analyzer_eval (a > b); /* { dg-warning "TRUE" } */
+}
+
+void test8 (size_t size)
+{
+ size_t a = size - 5;
+ size_t b = size - 1;
+ __analyzer_eval (a > b); /* { dg-warning "UNKNOWN" } */
+}
+
+void test9 (size_t size)
+{
+ size_t a = size + 1;
+ size_t b = size + 2;
+ __analyzer_eval (a > b); /* { dg-warning "UNKNOWN" } */
+}
+
+void test10 (size_t size)
+{
+ size_t a = size + 2;
+ size_t b = size + 1;
+ __analyzer_eval (a > b); /* { dg-warning "TRUE" } */
+}
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2022-09-08 17:47 [gcc r13-2546] analyzer: support for symbolic values in the out-of-bounds checker [PR106625] Tim Lange
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