Re: [musl] Segmentation fault musl 1.2.4

[Cody Wetzel <codyawetzel@gmail.com>]

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Sorry, I'm definitely not that well versed in linux.  I received the
following...

/ # /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) run
> Starting program: /bin/ls -l /tmp
> warning: Error disabling address space randomization: Operation not
> permitted
> warning: Could not trace the inferior process.
> warning: ptrace: Operation not permitted
> warning: Error restoring address space randomization: Operation not
> permitted
> During startup program exited with code 127.
>

Thanks!

On Thu, Jan 11, 2024 at 11:03 AM Szabolcs Nagy <nsz@port70.net> wrote:

> * Cody Wetzel <codyawetzel@gmail.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@port70.net> wrote:
> >
> > > * Cody Wetzel <codyawetzel@gmail.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@gmail.com
> > (402)490-9242
>


-- 
Cody Wetzel
codyawetzel@gmail.com
(402)490-9242

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