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Message-ID: <20240111170323.GP1427497@port70.net>
Date: Thu, 11 Jan 2024 18:03:23 +0100
From: Szabolcs Nagy <nsz@...t70.net>
To: Cody Wetzel <codyawetzel@...il.com>
Cc: Natanael Copa <ncopa@...inelinux.org>, musl@...ts.openwall.com,
Markus Wichmann <nullplan@....net>
Subject: Re: Segmentation fault musl 1.2.4
* Cody Wetzel <codyawetzel@...il.com> [2024-01-10 09:59:18 -0600]:
> So maybe I'm not understanding how gdb works or is used.
you have to run the process..
you never issued the gdb 'run' command.
> I'm getting no
> meaningful output even though these commands should result in a
> segmentation fault.
>
> > / # gdb
> > Segmentation fault
> > / # /tmp/ld-musl-armhf.so.1 /usr/bin/gdb --args ls -l /tmp
> > GNU gdb (GDB) 12.1
> > Copyright (C) 2022 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later <
> > http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law.
> > Type "show copying" and "show warranty" for details.
> > This GDB was configured as "armv7-alpine-linux-musleabihf".
> > Type "show configuration" for configuration details.
> > For bug reporting instructions, please see:
> > <https://www.gnu.org/software/gdb/bugs/>.
> > Find the GDB manual and other documentation resources online at:
> > <http://www.gnu.org/software/gdb/documentation/>.
> > For help, type "help".
> > Type "apropos word" to search for commands related to "word"...
> > Reading symbols from ls...
> > (No debugging symbols found in ls)
> > (gdb)
> > quit
> > / # /tmp/ld-musl-armhf.so.1 /usr/bin/gdb --args cd /tmp
> > GNU gdb (GDB) 12.1
> > Copyright (C) 2022 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later <
> > http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law.
> > Type "show copying" and "show warranty" for details.
> > This GDB was configured as "armv7-alpine-linux-musleabihf".
> > Type "show configuration" for configuration details.
> > For bug reporting instructions, please see:
> > <https://www.gnu.org/software/gdb/bugs/>.
> > Find the GDB manual and other documentation resources online at:
> > <http://www.gnu.org/software/gdb/documentation/>.
> > For help, type "help".
> > Type "apropos word" to search for commands related to "word"...
> > cd: No such file or directory.
> > (gdb)
> > quit
> > / # /tmp/ld-musl-armhf.so.1 /usr/bin/gdb --args apk -h /tmp
> > GNU gdb (GDB) 12.1
> > Copyright (C) 2022 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later <
> > http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law.
> > Type "show copying" and "show warranty" for details.
> > This GDB was configured as "armv7-alpine-linux-musleabihf".
> > Type "show configuration" for configuration details.
> > For bug reporting instructions, please see:
> > <https://www.gnu.org/software/gdb/bugs/>.
> > Find the GDB manual and other documentation resources online at:
> > <http://www.gnu.org/software/gdb/documentation/>.
> > For help, type "help".
> > Type "apropos word" to search for commands related to "word"...
> > Reading symbols from apk...
> > (No debugging symbols found in apk)
> > (gdb) bt
> > No stack.
> > (gdb) disas $pc-40,+80
> > No registers.
> > (gdb) info reg
> > The program has no registers now.
>
>
> On Thu, Jan 4, 2024 at 8:48 AM Szabolcs Nagy <nsz@...t70.net> wrote:
>
> > * Cody Wetzel <codyawetzel@...il.com> [2024-01-03 11:20:29 -0600]:
> > > Hello musl team,
> > >
> > > I tried getting a core dump but I'm not sure if I'm doing something
> > wrong...
> > >
> > > / # cat /proc/sys/kernel/core_pattern/tmp/core-%e-%s-%u-%g-%p-%t/ #
> > > apk upgrade busybox
> > > --repository=https://dl-cdn.alpinelinux.org/alpine/v3.18/main
> > > --repository=https://dl-cdn.alpinelinux.org/alpine/v3.18/communityfetch
> > >
> > https://dl-cdn.alpinelinux.org/alpine/v3.18/community/armv7/APKINDEX.tar.gzfetch
> > >
> > https://dl-cdn.alpinelinux.org/alpine/v3.18/main/armv7/APKINDEX.tar.gzfetch
> > >
> > https://dl-cdn.alpinelinux.org/alpine/v3.17/main/armv7/APKINDEX.tar.gzfetch
> > >
> > https://dl-cdn.alpinelinux.org/alpine/v3.17/community/armv7/APKINDEX.tar.gz(1/3)
> > > Upgrading busybox (1.35.0-r29 -> 1.36.1-r5)Executing
> > > busybox-1.36.1-r5.post-upgrade(2/3) Upgrading busybox-binsh
> > > (1.35.0-r29 -> 1.36.1-r5)(3/3) Upgrading ssl_client (1.35.0-r29 ->
> > > 1.36.1-r5)Executing busybox-1.36.1-r5.triggerOK: 5 MiB in 15 packages/
> > > # apk upgrade musl
> > > --repository=https://dl-cdn.alpinelinux.org/alpine/v3.18/main
> > > --repository=https://dl-cdn.alpinelinux.org/alpine/v3.18/community(1/1)
> > > Upgrading musl (1.2.3-r5 -> 1.2.4-r2)OK: 5 MiB in 15 packages/ # apk
> > > upgrade rust --repository=
> > https://dl-cdn.alpinelinux.org/alpine/v3.18/main
> > > --repository=
> > https://dl-cdn.alpinelinux.org/alpine/v3.18/communitySegmentation
> > > fault/ # apk -hSegmentation fault/ # ls /tmp/core*Segmentation fault/
> > > # cd /tmp/tmp # lsSegmentation fault
> >
> > i'd
> >
> > # cp /lib/ld-musl-armhf.so.1 /tmp
> > # apk add gdb musl-dbg apk-tools-static
> >
> > then upgrade musl using apk.static, then debug via
> >
> > # /tmp/ld-musl-armhf.so.1 /usr/bin/gdb --args ls -l /tmp
> >
> > or analyze a core dump, you can always install more debug tools
> > via apk.static and run commands using the old ld-musl-armhf.so.1
> >
> > in gdb, you want to do
> >
> > bt
> > disas $pc-40,+80
> > info reg
> > info proc map
> >
> > as a starting point and post the results.
> >
> > strace output can be useful too as well as readelf -aW of ld.so
> > depending on what is going on.
> >
>
>
> --
> Cody Wetzel
> codyawetzel@...il.com
> (402)490-9242
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