[gcc(refs/users/uecker/heads/vla)] c: Add Walloc-type to warn about insufficient size in allocations

[gcc(refs/users/uecker/heads/vla)] c: Add Walloc-type to warn about insufficient size in allocations

[Martin Uecker]

https://gcc.gnu.org/g:8e7176755cbd54d034050ff961ce72f885a83043

commit 8e7176755cbd54d034050ff961ce72f885a83043
Author: Martin Uecker <uecker@tugraz.at>
Date:   Thu Jul 27 13:36:05 2023 +0200

    c: Add Walloc-type to warn about insufficient size in allocations
    
    Add option Walloc-type that warns about allocations that have
    insufficient storage for the target type of the pointer the
    storage is assigned to.
    
    gcc:
            * doc/invoke.texi: Document -Walloc-type option.
    
    gcc/c-family:
    
            * c.opt (Walloc-type): New option.
    
    gcc/c:
            * c-typeck.cc (convert_for_assignment): Add Walloc-type warning.
    
    gcc/testsuite:
    
            * gcc.dg/Walloc-type-1.c: New test.

Diff:
---
 gcc/c-family/c.opt                   |  4 ++++
 gcc/c/c-typeck.cc                    | 26 +++++++++++++++++++++++++
 gcc/doc/invoke.texi                  | 10 ++++++++++
 gcc/testsuite/gcc.dg/Walloc-type-1.c | 37 ++++++++++++++++++++++++++++++++++++
 4 files changed, 77 insertions(+)

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 4abdc8d0e77..8b9d148582b 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -319,6 +319,10 @@ Walloca
 C ObjC C++ ObjC++ Var(warn_alloca) Warning
 Warn on any use of alloca.
 
+Walloc-type
+C ObjC Var(warn_alloc_type) Warning
+Warn when allocating insufficient storage for the target type of the assigned pointer.
+
 Walloc-size-larger-than=
 C ObjC C++ LTO ObjC++ Var(warn_alloc_size_limit) Joined Host_Wide_Int ByteSize Warning Init(HOST_WIDE_INT_MAX)
 -Walloc-size-larger-than=<bytes>	Warn for calls to allocation functions that
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 40e85450c33..5cd9c871d9f 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -7589,6 +7589,32 @@ convert_for_assignment_instrument (location_t location, location_t expr_loc, tre
 		    "request for implicit conversion "
 		    "from %qT to %qT not permitted in C++", rhstype, type);
 
+      /* Warn of new allocations are not big enough for the target type.  */
+      tree fndecl;
+      if (warn_alloc_type
+	  && TREE_CODE (rhs) == CALL_EXPR
+	  && (fndecl = get_callee_fndecl (rhs)) != NULL_TREE
+	  && DECL_IS_MALLOC (fndecl))
+	{
+	  tree fntype = TREE_TYPE (fndecl);
+	  tree fntypeattrs = TYPE_ATTRIBUTES (fntype);
+	  tree alloc_size = lookup_attribute ("alloc_size", fntypeattrs);
+	  if (alloc_size)
+	    {
+	      tree args = TREE_VALUE (alloc_size);
+	      int idx = TREE_INT_CST_LOW (TREE_VALUE (args)) - 1;
+	      /* For calloc only use the second argument.  */
+	      if (TREE_CHAIN (args))
+		idx = TREE_INT_CST_LOW (TREE_VALUE (TREE_CHAIN (args))) - 1;
+	      tree arg = CALL_EXPR_ARG (rhs, idx);
+	      if (TREE_CODE (arg) == INTEGER_CST
+		  && tree_int_cst_lt (arg, TYPE_SIZE_UNIT (ttl)))
+		 warning_at (location, OPT_Walloc_type, "allocation of "
+			     "insufficient size %qE for type %qT with "
+			     "size %qE", arg, ttl, TYPE_SIZE_UNIT (ttl));
+	    }
+	}
+
       /* See if the pointers point to incompatible address spaces.  */
       asl = TYPE_ADDR_SPACE (ttl);
       asr = TYPE_ADDR_SPACE (ttr);
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 578b4c31e4c..33fdd193df6 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8107,6 +8107,16 @@ Disable @option{-Walloc-size-larger-than=} warnings.  The option is
 equivalent to @option{-Walloc-size-larger-than=}@samp{SIZE_MAX} or
 larger.
 
+@opindex Wno-alloc-type
+@opindex Walloc-type
+@item -Walloc-type
+Warn about calls to allocation functions decorated with attribute
+@code{alloc_size} that specify insufficient size for the target type of
+the pointer the result is assigned to, including those to the built-in
+forms of the functions @code{aligned_alloc}, @code{alloca},
+@code{calloc},
+@code{malloc}, and @code{realloc}.
+
 @opindex Wno-alloca
 @opindex Walloca
 @item -Walloca
diff --git a/gcc/testsuite/gcc.dg/Walloc-type-1.c b/gcc/testsuite/gcc.dg/Walloc-type-1.c
new file mode 100644
index 00000000000..bc62e5e9aa3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Walloc-type-1.c
@@ -0,0 +1,37 @@
+/* Tests the warnings for insufficient allocation size. 
+   { dg-do compile }
+ * { dg-options "-Walloc-type" } 
+ * */
+#include <stdlib.h>
+#include <alloca.h>
+
+struct b { int x[10]; };
+
+void fo0(void)
+{
+        struct b *p = malloc(sizeof *p);
+}
+
+void fo1(void)
+{
+        struct b *p = malloc(sizeof p);		/* { dg-warning "allocation of insufficient size" } */
+}
+
+void fo2(void)
+{
+        struct b *p = alloca(sizeof p);		/* { dg-warning "allocation of insufficient size" } */
+}
+
+void fo3(void)
+{
+        struct b *p = calloc(1, sizeof p);	/* { dg-warning "allocation of insufficient size" } */
+}
+
+void g(struct b* p);
+
+void fo4(void)
+{
+        g(malloc(4));		/* { dg-warning "allocation of insufficient size" } */
+}
+
+