glibc/debug
Joan Bruguera 33e03f9cd2 misc: Fix rare fortify crash on wchar funcs. [BZ 29030]
If `__glibc_objsize (__o) == (size_t) -1` (i.e. `__o` is unknown size), fortify
checks should pass, and `__whatever_alias` should be called.

Previously, `__glibc_objsize (__o) == (size_t) -1` was explicitly checked, but
on commit a643f60c53, this was moved into `__glibc_safe_or_unknown_len`.

A comment says the -1 case should work as: "The -1 check is redundant because
since it implies that __glibc_safe_len_cond is true.". But this fails when:
* `__s > 1`
* `__osz == -1` (i.e. unknown size at compile time)
* `__l` is big enough
* `__l * __s <= __osz` can be folded to a constant
(I only found this to be true for `mbsrtowcs` and other functions in wchar2.h)

In this case `__l * __s <= __osz` is false, and `__whatever_chk_warn` will be
called by `__glibc_fortify` or `__glibc_fortify_n` and crash the program.

This commit adds the explicit `__osz == -1` check again.
moc crashes on startup due to this, see: https://bugs.archlinux.org/task/74041

Minimal test case (test.c):
    #include <wchar.h>

    int main (void)
    {
        const char *hw = "HelloWorld";
        mbsrtowcs (NULL, &hw, (size_t)-1, NULL);
        return 0;
    }

Build with:
    gcc -O2 -Wp,-D_FORTIFY_SOURCE=2 test.c -o test && ./test

Output:
    *** buffer overflow detected ***: terminated

Fixes: BZ #29030
Signed-off-by: Joan Bruguera <joanbrugueram@gmail.com>
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-04-25 17:32:30 +05:30
..
asprintf_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
backtrace-tst.c Add #include <stdint.h> for uint[32|64]_t usage (except installed headers). 2013-05-16 11:32:54 -05:00
backtrace.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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confstr_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
Depend * stdlib/bits/stdlib.h: New file. 2005-07-13 06:09:58 +00:00
dprintf_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
execinfo.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
explicit_bzero_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
fdelt_chk.c debug: Improve fdelt_chk error message 2022-03-28 19:10:30 +05:30
fgets_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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fgetws_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
fgetws_u_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
fortify_fail.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
fprintf_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
fread_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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fwprintf_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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longjmp_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
Makefile debug: Synchronize feature guards in fortified functions [BZ #28746] 2022-01-12 23:34:48 +05:30
mbsnrtowcs_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mbsrtowcs_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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pcprofile.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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poll_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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tst-fortify.c misc: Fix rare fortify crash on wchar funcs. [BZ 29030] 2022-04-25 17:32:30 +05:30
tst-longjmp_chk2.c Remove "Contributed by" lines 2021-09-03 22:06:44 +05:30
tst-longjmp_chk3.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-longjmp_chk.c tests: unify fortification handler logic 2014-02-08 06:58:43 -05:00
tst-realpath-chk.c fortify: Fix spurious warning with realpath 2021-12-17 18:49:27 +05:30
tst-ssp-1.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
ttyname_r_chk.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
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Versions New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
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