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From: priour.be@gmail.com
To: gcc-patches@gcc.gnu.org
Cc: dmalcolm@redhat.com, benjamin priour <priour.be@gmail.com>
Subject: 
Date: Thu, 22 Jun 2023 21:49:54 +0200	[thread overview]
Message-ID: <20230622194952.1834364-1-vultkayn@gcc.gnu.org> (raw)

Hi,

Below is the fix to regression bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110198
Was bootstrapped and regtested successfully on x86_64-linux-gnu
Considering mishap from last patch, I'd would appreciate if you could
also regtest it, to be sure :)

Thanks,
Benjamin.

From 04186f04a3f172d7ccf9824cc71faca489eb39af Mon Sep 17 00:00:00 2001
From: benjamin priour <priour.be@gmail.com>
Date: Thu, 22 Jun 2023 21:39:05 +0200
Subject: [PATCH] [PATCH] analyzer: Fix regression bug after
 r14-1632-g9589a46ddadc8b [pr110198]

g++.dg/analyzer/pr100244.C was failing after a patch of PR109439.
The reason was a spurious preemptive return of get_store_value upon out-of-bounds read that
was preventing further checks. Now instead, a boolean value check_poisoned goes to false when
a OOB is detected, and is later on given to get_or_create_initial_value.

gcc/analyzer/ChangeLog:

	* region-model-manager.cc (region_model_manager::get_or_create_initial_value): Take an
		optional boolean value to bypass poisoning checks
	* region-model-manager.h: Update declaration of the above function.
	* region-model.cc (region_model::get_store_value): No longer
		returns on OOB, but rather gives a boolean to get_or_create_initial_value.
	(region_model::check_region_access): Update docstring.
	(region_model::check_region_for_write): Update docstring.

Signed-off-by: benjamin priour <priour.be@gmail.com>
---
 gcc/analyzer/region-model-manager.cc |  5 +++--
 gcc/analyzer/region-model-manager.h  |  3 ++-
 gcc/analyzer/region-model.cc         | 15 ++++++++-------
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/gcc/analyzer/region-model-manager.cc b/gcc/analyzer/region-model-manager.cc
index 1453acf7bc9..4f11ef4bd29 100644
--- a/gcc/analyzer/region-model-manager.cc
+++ b/gcc/analyzer/region-model-manager.cc
@@ -293,9 +293,10 @@ region_model_manager::create_unique_svalue (tree type)
    necessary.  */
 
 const svalue *
-region_model_manager::get_or_create_initial_value (const region *reg)
+region_model_manager::get_or_create_initial_value (const region *reg,
+						   bool check_poisoned)
 {
-  if (!reg->can_have_initial_svalue_p ())
+  if (!reg->can_have_initial_svalue_p () && check_poisoned)
     return get_or_create_poisoned_svalue (POISON_KIND_UNINIT,
 					  reg->get_type ());
 
diff --git a/gcc/analyzer/region-model-manager.h b/gcc/analyzer/region-model-manager.h
index 3340c3ebd1e..ff5333bf07c 100644
--- a/gcc/analyzer/region-model-manager.h
+++ b/gcc/analyzer/region-model-manager.h
@@ -49,7 +49,8 @@ public:
 					     tree type);
   const svalue *get_or_create_poisoned_svalue (enum poison_kind kind,
 					       tree type);
-  const svalue *get_or_create_initial_value (const region *reg);
+  const svalue *get_or_create_initial_value (const region *reg,
+					     bool check_poisoned = true);
   const svalue *get_ptr_svalue (tree ptr_type, const region *pointee);
   const svalue *get_or_create_unaryop (tree type, enum tree_code op,
 				       const svalue *arg);
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index 6bc60f89f3d..187013a37cc 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -2373,8 +2373,9 @@ region_model::get_store_value (const region *reg,
   if (reg->empty_p ())
     return m_mgr->get_or_create_unknown_svalue (reg->get_type ());
 
+  bool check_poisoned = true;
   if (check_region_for_read (reg, ctxt))
-    return m_mgr->get_or_create_unknown_svalue(reg->get_type());
+    check_poisoned = false;
 
   /* Special-case: handle var_decls in the constant pool.  */
   if (const decl_region *decl_reg = reg->dyn_cast_decl_region ())
@@ -2427,7 +2428,7 @@ region_model::get_store_value (const region *reg,
       == RK_GLOBALS)
     return get_initial_value_for_global (reg);
 
-  return m_mgr->get_or_create_initial_value (reg);
+  return m_mgr->get_or_create_initial_value (reg, check_poisoned);
 }
 
 /* Return false if REG does not exist, true if it may do.
@@ -2790,7 +2791,7 @@ region_model::get_string_size (const region *reg) const
 
 /* If CTXT is non-NULL, use it to warn about any problems accessing REG,
    using DIR to determine if this access is a read or write.
-   Return TRUE if an UNKNOWN_SVALUE needs be created.
+   Return TRUE if an OOB access was detected.
    If SVAL_HINT is non-NULL, use it as a hint in diagnostics
    about the value that would be written to REG.  */
 
@@ -2804,10 +2805,10 @@ region_model::check_region_access (const region *reg,
   if (!ctxt)
     return false;
 
-  bool need_unknown_sval = false;
+  bool oob_access_detected = false;
   check_region_for_taint (reg, dir, ctxt);
   if (!check_region_bounds (reg, dir, sval_hint, ctxt))
-    need_unknown_sval = true;
+    oob_access_detected = true;
 
   switch (dir)
     {
@@ -2820,7 +2821,7 @@ region_model::check_region_access (const region *reg,
       check_for_writable_region (reg, ctxt);
       break;
     }
-  return need_unknown_sval;
+  return oob_access_detected;
 }
 
 /* If CTXT is non-NULL, use it to warn about any problems writing to REG.  */
@@ -2834,7 +2835,7 @@ region_model::check_region_for_write (const region *dest_reg,
 }
 
 /* If CTXT is non-NULL, use it to warn about any problems reading from REG.
-  Returns TRUE if an unknown svalue needs be created.  */
+  Returns TRUE if an OOB read was detected.  */
 
 bool
 region_model::check_region_for_read (const region *src_reg,
-- 
2.34.1


                 reply	other threads:[~2023-06-22 19:54 UTC|newest]

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