Re: glibc 2.36 build failure on Fedora 36 with gcc 12 (-Werror=use-after-free)

[Sunil Pandey <skpgkp2@gmail.com>]

On Fri, Jul 29, 2022 at 8:43 AM Sunil Pandey <skpgkp2@gmail.com> wrote:
>
> On Fri, Jul 29, 2022 at 8:26 AM Carlos O'Donell via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
> >
> > Just posting here for the record that I see a glibc 2.36 build failure
> > with Fedora 36 and gcc 12.
> >
> > localealias.c: In function ‘read_alias_file’:
> > localealias.c:335:56: error: pointer may be used after ‘realloc’ [-Werror=use-after-free]
> >   335 |                               map[i].alias += new_pool - string_space;
> >       |                                               ~~~~~~~~~^~~~~~~~~~~~~~
> > localealias.c:325:49: note: call to ‘realloc’ here
> >   325 |                       char *new_pool = (char *) realloc (string_space, new_size);
> >       |                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > cc1: all warnings being treated as errors
> >
> > I'm going to review this quickly before we make the glibc release.
> >
> > --
> > Cheers,
> > Carlos.
> >
>
> I am getting these 2 wide string test failures on my SKX server.
>
> FAIL: wcsmbs/test-c8rtomb (Not reproducible)
>
> FAIL: wcsmbs/test-mbrtoc8
>
> $ wcsmbs/test-mbrtoc8
> test-mbrtoc8.c:477: numeric comparison failure
>    left: 2 (0x2); from: mbrtoc8 (buf, mbs, 1, &s)
>   right: 1 (0x1); from: (size_t) 1
> test-mbrtoc8.c:479: numeric comparison failure
>    left: 0 (0x0); from: buf[0]
>   right: 195 (0xc3); from: 0xC3
> test-mbrtoc8.c:481: numeric comparison failure
>    left: 204 (0xcc); from: buf[0]
>   right: 138 (0x8a); from: 0x8A
> test-mbrtoc8.c:483: numeric comparison failure
>    left: 132 (0x84); from: buf[0]
>   right: 204 (0xcc); from: 0xCC
> test-mbrtoc8.c:484: numeric comparison failure
>    left: 0 (0x0); from: mbrtoc8 (buf, mbs, 1, &s)
>   right: 18446744073709551613 (0xfffffffffffffffd); from: (size_t) -3
> test-mbrtoc8.c:485: numeric comparison failure
>    left: 0 (0x0); from: buf[0]
>   right: 132 (0x84); from: 0x84
> test-mbrtoc8.c:516: numeric comparison failure
>    left: 2 (0x2); from: mbrtoc8 (buf, mbs, 1, &s)
>   right: 1 (0x1); from: (size_t) 1
> test-mbrtoc8.c:518: numeric comparison failure
>    left: 0 (0x0); from: buf[0]
>   right: 195 (0xc3); from: 0xC3
> test-mbrtoc8.c:520: numeric comparison failure
>    left: 204 (0xcc); from: buf[0]
>   right: 170 (0xaa); from: 0xAA
> test-mbrtoc8.c:522: numeric comparison failure
>    left: 140 (0x8c); from: buf[0]
>   right: 204 (0xcc); from: 0xCC
> test-mbrtoc8.c:523: numeric comparison failure
>    left: 0 (0x0); from: mbrtoc8 (buf, mbs, 1, &s)
>   right: 18446744073709551613 (0xfffffffffffffffd); from: (size_t) -3
> test-mbrtoc8.c:524: numeric comparison failure
>    left: 0 (0x0); from: buf[0]
>   right: 140 (0x8c); from: 0x8C
> error: 12 test failures

These 2 tests fail on their first commit itself, unless this issue
is specific to my machine.

commit f4fe72a4f7b22588a7c902e39ddd3dcd244bbf9f (HEAD)
Author: Tom Honermann <tom@honermann.net>
Date:   Thu Jun 30 08:52:15 2022 -0400

    stdlib: Tests for mbrtoc8, c8rtomb, and the char8_t typedef.