[PATCH v2] Fix stringop-overflow warning in bug-regex19.c.
Stefan Liebler
stli@linux.ibm.com
Tue May 18 08:09:48 GMT 2021
On 17/05/2021 16:19, Stefan Liebler wrote:
> Starting with commit
> 26492c0a14966c32c43cd6ca1d0dca5e62c6cfef
> "Annotate additional APIs with GCC attribute access.",
> gcc emits this warning on s390x:
> In function ‘do_one_test’,
> inlined from ‘do_mb_tests’ at bug-regex19.c:385:11:
> bug-regex19.c:271:9: error: ‘re_search’ specified size 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Werror=stringop-overflow=]
> 271 | res = re_search (®buf, test->string, strlen (test->string),
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 272 | test->start, strlen (test->string) - test->start, NULL);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from ../include/regex.h:2,
> from bug-regex19.c:22:
> bug-regex19.c: In function ‘do_mb_tests’:
> ../posix/regex.h:554:17: note: in a call to function ‘re_search’ declared with attribute ‘read_only (2, 3)’
> 554 | extern regoff_t re_search (struct re_pattern_buffer *__buffer,
> | ^~~~~~~~~
> ...
>
> The function do_one_test is inlined into do_mb_tests on s390x (at least with
> gcc 10). If do_one_test is marked with __attribute__ ((noinline)), there are
> no warnings on s390x. If do_one_test is marked with
> __attribute__ ((always_inline)), there are the same warnings on x86_64.
>
> test->string points to a variable length array on stack of do_mb_tests
> and the content is generated based on the passed test struct.
>
> According to Martin Sebor, this is a false positive caused by the same bug as
> the one in nss/makedb.c. It's fixed in GCC 11 and will also be available in
> the next GCC 10.4 release.
> ---
> posix/bug-regex19.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/posix/bug-regex19.c b/posix/bug-regex19.c
> index 9bbffb17e3..b3fee0a730 100644
> --- a/posix/bug-regex19.c
> +++ b/posix/bug-regex19.c
> @@ -24,6 +24,7 @@
> #include <stdlib.h>
> #include <string.h>
> #include <locale.h>
> +#include <libc-diag.h>
>
> #define BRE RE_SYNTAX_POSIX_BASIC
> #define ERE RE_SYNTAX_POSIX_EXTENDED
> @@ -268,8 +269,17 @@ do_one_test (const struct test_s *test, const char *fail)
> return 1;
> }
>
> +#if __GNUC_PREREQ (10, 0) && !__GNUC_PREREQ (11, 0)
> + DIAG_PUSH_NEEDS_COMMENT;
> + /* Avoid GCC 10 false positive warning: specified size exceeds maximum
> + object size. */
> + DIAG_IGNORE_NEEDS_COMMENT (10, "-Wstringop-overflow");
> +#endif
> res = re_search (®buf, test->string, strlen (test->string),
> test->start, strlen (test->string) - test->start, NULL);
> +#if __GNUC_PREREQ (10, 0) && !__GNUC_PREREQ (11, 0)
> + DIAG_POP_NEEDS_COMMENT;
> +#endif
> if (res != test->res)
> {
> printf ("%sre_search \"%s\" \"%s\" failed: %d (expected %d)\n",
> @@ -280,8 +290,17 @@ do_one_test (const struct test_s *test, const char *fail)
>
> if (test->res > 0 && test->start == 0)
> {
> +#if __GNUC_PREREQ (10, 0) && !__GNUC_PREREQ (11, 0)
> + DIAG_PUSH_NEEDS_COMMENT;
> + /* Avoid GCC 10 false positive warning: specified size exceeds maximum
> + object size. */
> + DIAG_IGNORE_NEEDS_COMMENT (10, "-Wstringop-overflow");
> +#endif
> res = re_search (®buf, test->string, strlen (test->string),
> test->res, strlen (test->string) - test->res, NULL);
> +#if __GNUC_PREREQ (10, 0) && !__GNUC_PREREQ (11, 0)
> + DIAG_POP_NEEDS_COMMENT;
> +#endif
> if (res != test->res)
> {
> printf ("%sre_search from expected \"%s\" \"%s\" failed: %d (expected %d)\n",
>
Committed after response from Martin:
https://sourceware.org/pipermail/libc-alpha/2021-May/126416.html
Thanks,
Stefan
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