[Bug gdb/30207] New: GDB crashes on processing Apache2 crash dump

[Bug gdb/30207] New: GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

            Bug ID: 30207
           Summary: GDB crashes on processing Apache2 crash dump
           Product: gdb
           Version: 12.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: pastas at learn4good dot com
  Target Milestone: ---

Created attachment 14738
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14738&action=edit
GDB core dump

GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1

Architecture: amd64


Command run: gdb /usr/sbin/apache2 CoreDump

Then processed GDB core dump of its own and made output which I have attached
which I hope is of help.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simark at simark dot ca

--- Comment #1 from Simon Marchi <simark at simark dot ca> ---
Since you are on Ubuntu, you could perhaps install the dbgsym package for gdb,
to get better backtraces.

https://wiki.ubuntu.com/Debug%20Symbol%20Packages

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #2 from Erlandas <pastas at learn4good dot com> ---
Tried following those instructions and have tried:

apt-get install gdb-dbgsym

which gives:

The following packages have unmet dependencies:
 gdb-dbgsym : Depends: gdb (= 12.0.90-0ubuntu1) but 12.1-0ubuntu1~22.04 is to
be installed

Yes, debug symbol package could provide more valuable info.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #3 from Simon Marchi <simark at simark dot ca> ---
Ah, that's unfortunate, it must be that the dbgsym package is out of date.

Alternatively, you can build GDB yourself, it's quite simple, just ./configure
&& make.  There are only a few dependencies that are very common packages.

Another option would be for you to upload your executable and core, see if
somebody else can reproduce.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #4 from Erlandas <pastas at learn4good dot com> ---
Have removed version 12.1 which comes with "apt install gdb"

Built version 13.1 from source. But I do not see gdb-dbgsym executable. Am I
missing something or did I have to build it with some additional config?

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[simon.marchi at polymtl dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

Simon Marchi <simon.marchi at polymtl dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simon.marchi at polymtl dot ca

--- Comment #5 from Simon Marchi <simon.marchi at polymtl dot ca> ---
(In reply to Erlandas from comment #4)
> Have removed version 12.1 which comes with "apt install gdb"
> 
> Built version 13.1 from source. But I do not see gdb-dbgsym executable. Am I
> missing something or did I have to build it with some additional config?

If you build it from source, you wouldn't use the dbgsym package.  The dbgsym
packages contain debug info matching the binaries distributed in the distro
packages.

When configuring (./configure) GDB, pass:

  CFLAGS="-g -O0" CXXFLAGS="-g -O0"

That will make it build with no optimizations (it will be slower, but easier to
debug) and with debug info directly inside the binary.

Btw, since you are using Ubuntu 22.04, you could have also configured the
top-level GDB to use debuginfod, as described here:

https://wiki.ubuntu.com/Debug%20Symbol%20Packages#Debuginfod

This is pretty cool, it makes GDB download debug info for distro packages
transparently, when it needs it.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #6 from Erlandas <pastas at learn4good dot com> ---
I have finally got a possibly reproducible case where I still have a core dump
which I was trying to debug and it in turn made GDB crash itself. This time it
is not Apache, but ManticoreSearch Core Dump.

The commands used on Ubuntu 22:

cd /var/crash;mkdir searchd;apport-unpack _usr_bin_searchd.1003.crash
searchd;cd searchd;gdb /usr/bin/searchd CoreDump

Then:

set pagination off
set logging on
info threads
thread apply all bt
bt full
info locals
detach


Where it crashed on INFO LOCALS or DETACH. searchd process core file is about
500 Kb, GDB core dump is 50Mb.

Tried processing GDB own coredump and on DETACH it crashed again. Processing
core dump did not show any symbols of its own

WHere /how do I provide both core dumps for someone to examine them?

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #7 from Simon Marchi <simark at simark dot ca> ---
You could try to attach the searchd binary and the searchd core dump to this
bug.  If it's too big to attach directly, upload it somewhere and provide the
link.

The GDB coredump is likely only useful to you, if you did your own build.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #8 from Erlandas <pastas at learn4good dot com> ---
Created attachment 14797
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14797&action=edit
Searchd (ManticoreSearch) Binary

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #9 from Erlandas <pastas at learn4good dot com> ---
Created attachment 14798
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14798&action=edit
Searchd crash core dump

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[pastas at learn4good dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

--- Comment #10 from Erlandas <pastas at learn4good dot com> ---
Attached coredump which make GDB crash and binary which produced the crash
dump.

Gdb does process the core dump as per my instructions below, but crashes on 
DETACH.

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[Bug gdb/30207] GDB crashes on processing Apache2 crash dump

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=30207

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #11 from Simon Marchi <simark at simark dot ca> ---
I tried reproducing on an Ubuntu 22.04 system, using a recent build from
master, but got:

(gdb) detach
No core file now.

But I then realized that all this time I was not using the gdb from the distro,
as I thought, but a more recent build.  With /usr/bin/gdb, I do get a crash
when trying to "detach" a core.

It was fixed by this commit:

https://gitlab.com/gnutools/binutils-gdb/-/commit/0fe74cb9ad35add9c6da4df5c9879f254d918a6a

*** This bug has been marked as a duplicate of bug 29275 ***

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