glibc: the x86 mem[r]chr changes cause random segfaults

[Dorian ROSSE]

Hello the libc alpha team,


I don't success to install glibc,

I have follow the readme but this doesn't work,

Please can you help myself the e-mail send has now one or two month I have set up some options for the building without success,

Thanks you in advance for your help,

Regards.


Dorian Rosse.
________________________________
From: Libc-alpha <libc-alpha-bounces+dorianbrice=hotmail.fr@sourceware.org> on behalf of H.J. Lu via Libc-alpha <libc-alpha@sourceware.org>
Sent: Wednesday, June 8, 2022 8:57:11 PM
To: Manuel Lauss <manuel.lauss@gmail.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: glibc: the x86 mem[r]chr changes cause random segfaults

On Wed, Jun 8, 2022 at 11:22 AM Manuel Lauss via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> Hi Noah,
>
> One of your recent x86 mem[r]chr patches to glibc causes random segfaults in
> gcc;  I haven't nailed it down to a single patch yet, but a glibc built
> up to commit 0218463dd8265ed937622f88ac68c7d984fe0cfc (all your
> commits from 07th June reverted) works just fine.
> For me it's very easy to reproduce, just rebuild glibc.
>
> The backtraces all look like this (sorry, no debug symbols for gcc):
> #0  0x00007fdd9df1d36a in __GI___libc_free (mem=0x672f7ffcc7137ff0) at
> malloc.c:3368
> warning: Source file is more recent than executable.
> 3368      if (chunk_is_mmapped (p))                       /* release
> mmapped memory. */
> (gdb) bt
> #0  0x00007fdd9df1d36a in __GI___libc_free (mem=0x672f7ffcc7137ff0) at
> malloc.c:3368
> #1  0x00007fdd9debe3e0 in scratch_buffer_free (buffer=0x7ffcc7137fe0)
> at ../include/scratch_buffer.h:86
> #2  realpath_stk (name=<optimized out>, resolved=<optimized out>,
> rname_buf=rname_buf@entry=0x7ffcc7137fe0) at canonicalize.c:423
> #3  0x00007fdd9debeaff in __GI___realpath (name=<optimized out>,
> resolved=<optimized out>) at canonicalize.c:449

I suspect that rawmemchr isn't properly handled.

> #4  0x000000000048b818 in ?? ()
> #5  0x000000000048a62c in ?? ()
> #6  0x000000000040d9b4 in ?? ()
> #7  0x0000000000416b62 in ?? ()
> #8  0x00000000004054e9 in ?? ()
> #9  0x0000000000405a89 in ?? ()
> #10 0x00007fdd9dea82b7 in __libc_start_call_main
> (main=main@entry=0x405a60, argc=argc@entry=103,
> argv=argv@entry=0x7ffcc7139708)
>    at ../sysdeps/nptl/libc_start_call_main.h:58
> #11 0x00007fdd9dea8375 in __libc_start_main_impl (main=0x405a60,
> argc=103, argv=0x7ffcc7139708, init=<optimized out>, fini=<optimized
> out>, rtld_fini=<optimized out>,
>    stack_end=0x7ffcc71396f8) at ../csu/libc-start.c:381
> #12 0x0000000000405bb1 in ?? ()
>
> Thanks,
>       Manuel



--
H.J.