[PING] [C PATCH, v2] Add Walloc-size to warn about insufficient size in allocations [PR71219]
Am Montag, dem 18.09.2023 um 23:26 +0200 schrieb Martin Uecker:
>
> Compared to the previous version I changed the name of the
> warning to "Walloc-size" which matches "Wanalyzer-allocation-size"
> but is still in line with the other -Walloc-something warnings
> we have. I also added it to Wextra.
>
> I found PR71219 that requests the warning and points out that
> it is recommended by the C secure coding guidelines and added
> the PR to the commit log (although the version with cast is not
> diagnosed so far.)
>
> I did not have time to implement the extensions suggested
> on the list, i.e. warn when the size is not a multiple
> of the size of the type and warn for if the size is not
> suitable for a flexible array member. (this is also a bit
> more complicated than it seems)
>
> Bootstrapped and regression tested on x86_64.
>
>
> Martin
>
>
> Add option Walloc-size that warns about allocations that have
> insufficient storage for the target type of the pointer the
> storage is assigned to.
>
> PR c/71219
> gcc:
> * doc/invoke.texi: Document -Walloc-size option.
>
> gcc/c-family:
>
> * c.opt (Walloc-size): New option.
>
> gcc/c:
> * c-typeck.cc (convert_for_assignment): Add warning.
>
> gcc/testsuite:
>
> * gcc.dg/Walloc-size-1.c: New test.
> ---
> gcc/c-family/c.opt | 4
> gcc/c/c-typeck.cc| 27 +
> gcc/doc/invoke.texi | 10
> gcc/testsuite/gcc.dg/Walloc-size-1.c | 36
> 4 files changed, 77 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/Walloc-size-1.c
>
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index 7348ad42ee0..9ba08a1fb6d 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-size
> +C ObjC Var(warn_alloc_size) 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= Warn for calls to allocation functions
> that
> diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
> index e2bfd2caf85..c759c6245ed 100644
> --- a/gcc/c/c-typeck.cc
> +++ b/gcc/c/c-typeck.cc
> @@ -7384,6 +7384,33 @@ convert_for_assignment (location_t location,
> location_t expr_loc, tree type,
> "request for implicit conversion "
> "from %qT to %qT not permitted in C++", rhstype, type);
>
> + /* Warn of new allocations that are not big enough for the target
> + type. */
> + tree fndecl;
> + if (warn_alloc_size
> + && 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_size, "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 33befee7d6b..a4fbcf5e1b5 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -8086,6 +8086,16 @@ always leads to a call to another @code{cold} function
> such as wrappers of
> C++ @code{throw} or fatal error reporting functions leading to @code{abort}.
> @end table
>
> +@opindex Wno-alloc-size
> +@opindex Walloc-size
> +@item -Walloc-size
> +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-alloc-zero
> @opindex Walloc-zero
> @item -Walloc-zero
> diff --git a/gcc/testsuite/gcc.dg/Walloc-size-1.c
> b/gcc/testsuite/gcc.dg/Walloc-size-1.c
> new file mode 10
Re: [PING] [C PATCH, v2] Add Walloc-size to warn about insufficient size in allocations [PR71219]
On Tue, 31 Oct 2023, Martin Uecker wrote: > > + if (TREE_CODE (arg) == INTEGER_CST > > + && tree_int_cst_lt (arg, TYPE_SIZE_UNIT (ttl))) What if TYPE_SIZE_UNIT (ttl) is not an INTEGER_CST? I don't see any tests of the case of assigning to a pointer to a variably sized type. -- Joseph S. Myers jos...@codesourcery.com
Re: [PING] [C PATCH, v2] Add Walloc-size to warn about insufficient size in allocations [PR71219]
Am Dienstag, dem 31.10.2023 um 22:19 + schrieb Joseph Myers:
> On Tue, 31 Oct 2023, Martin Uecker wrote:
>
> > > + if (TREE_CODE (arg) == INTEGER_CST
> > > + && tree_int_cst_lt (arg, TYPE_SIZE_UNIT (ttl)))
>
> What if TYPE_SIZE_UNIT (ttl) is not an INTEGER_CST? I don't see any tests
> of the case of assigning to a pointer to a variably sized type.
>
Right. Thanks! Revised version attached.
Martin
c: Add Walloc-size to warn about insufficient size in allocations [PR71219]
Add option Walloc-size that warns about allocations that have
insufficient storage for the target type of the pointer the
storage is assigned to. Added to Wextra.
PR c/71219
gcc:
* doc/invoke.texi: Document -Walloc-size option.
gcc/c-family:
* c.opt (Walloc-size): New option.
gcc/c:
* c-typeck.cc (convert_for_assignment): Add warning.
gcc/testsuite:
* gcc.dg/Walloc-size-1.c: New test.
* gcc.dg/Walloc-size-2.c: New test.
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 44b9c862c14..29d3d789a49 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -331,6 +331,10 @@ Walloca
C ObjC C++ ObjC++ Var(warn_alloca) Warning
Warn on any use of alloca.
+Walloc-size
+C ObjC Var(warn_alloc_size) Warning LangEnabledBy(C ObjC, Wextra)
+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= Warn for calls to allocation functions
that
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 0de4662bfc6..16fadfb5468 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -7347,6 +7347,34 @@ convert_for_assignment (location_t location, location_t
expr_loc, tree type,
"request for implicit conversion "
"from %qT to %qT not permitted in C++", rhstype, type);
+ /* Warn of new allocations that are not big enough for the target
+type. */
+ tree fndecl;
+ if (warn_alloc_size
+ && 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
+ && INTEGER_CST == TREE_CODE (TYPE_SIZE_UNIT (ttl))
+ && tree_int_cst_lt (arg, TYPE_SIZE_UNIT (ttl)))
+warning_at (location, OPT_Walloc_size, "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 5a9284d635c..815a33d4b87 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8138,6 +8138,16 @@ always leads to a call to another @code{cold} function
such as wrappers of
C++ @code{throw} or fatal error reporting functions leading to @code{abort}.
@end table
+@opindex Wno-alloc-size
+@opindex Walloc-size
+@item -Walloc-size
+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-alloc-zero
@opindex Walloc-zero
@item -Walloc-zero
diff --git a/gcc/testsuite/gcc.dg/Walloc-size-1.c
b/gcc/testsuite/gcc.dg/Walloc-size-1.c
new file mode 100644
index 000..61806f58192
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Walloc-size-1.c
@@ -0,0 +1,36 @@
+/* Tests the warnings for insufficient allocation size.
+ { dg-do compile }
+ { dg-options "-Walloc-size" }
+ * */
+#include
+#include
+
+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
Re: [PING] [C PATCH, v2] Add Walloc-size to warn about insufficient size in allocations [PR71219]
On Wed, 1 Nov 2023, Martin Uecker wrote: > Am Dienstag, dem 31.10.2023 um 22:19 + schrieb Joseph Myers: > > On Tue, 31 Oct 2023, Martin Uecker wrote: > > > > > > + if (TREE_CODE (arg) == INTEGER_CST > > > > + && tree_int_cst_lt (arg, TYPE_SIZE_UNIT (ttl))) > > > > What if TYPE_SIZE_UNIT (ttl) is not an INTEGER_CST? I don't see any tests > > of the case of assigning to a pointer to a variably sized type. > > > > Right. Thanks! Revised version attached. This version is OK. -- Joseph S. Myers jos...@codesourcery.com
