[git] bugreport of a segmentation fault

[git] bugreport of a segmentation fault

[Morten Bo Johansen]

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In the attachment, I have reported a segmentation fault in git.

Regards,
Morten

[-- Attachment #2: git-bugreport-2024-12-22-1816.txt --]
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Thank you for filling out a Git bug report!
Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)

I had first run the command

   git difftool --no-symlinks --dir-diff

to show a diff between a modified file I intended to commit. After the commit
I ran the command again and git crashed.

What did you expect to happen? (Expected behavior)

  I expected git to show an empty output since the modified file had been
  committed.

What happened instead? (Actual behavior)

  It crashed.

What's different between what you expected and what actually happened?

  The crash

Anything else you want to add:

  Here is the trace which I hope is useful:

    ~/ % coredumpctl debug
               PID: 220080 (git)
               UID: 1000 (mojo)
               GID: 1000 (mojo)
            Signal: 11 (SEGV)
         Timestamp: Sun 2024-12-22 17:55:51 CET (13min ago)
      Command Line: git difftool --no-symlinks --dir-diff
        Executable: /usr/bin/git
     Control Group: /user.slice/user-1000.slice/user@1000.service/kitty-1421-3.scope
              Unit: user@1000.service
         User Unit: kitty-1421-3.scope
             Slice: user-1000.slice
         Owner UID: 1000 (mojo)
           Boot ID: 22b76570d3a848bb9c8ab817b3f01126
        Machine ID: 81a58827c2a04d8185f0370a425305ca
          Hostname: gatsby
           Storage: /var/lib/systemd/coredump/core.git.1000.22b76570d3a848bb9c8ab817b3f01126.220080.1734886551000000.zst (present)
      Size on Disk: 46.4K
           Message: Process 220080 (git) of user 1000 dumped core.
    
                    Stack trace of thread 220080:
                    #0  0x000060193ce06513 n/a (n/a + 0x0)
                    #1  0x000060193cc845c0 n/a (n/a + 0x0)
                    #2  0x000060193cc2e454 n/a (n/a + 0x0)
                    #3  0x000060193cc2ead9 n/a (n/a + 0x0)
                    #4  0x000060193cc297eb n/a (n/a + 0x0)
                    #5  0x00007a67eb5dee08 n/a (libc.so.6 + 0x25e08)
                    #6  0x00007a67eb5deecc __libc_start_main (libc.so.6 + 0x25ecc)
                    #7  0x000060193cc29cb5 n/a (n/a + 0x0)
                    ELF object binary architecture: AMD x86-64
    
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    For help, type "help".
    Type "apropos word" to search for commands related to "word"...
    Reading symbols from /usr/bin/git...

    This GDB supports auto-downloading debuginfo from the following URLs:
      <https://debuginfod.archlinux.org>
    Enable debuginfod for this session? (y or [n]) y
    Debuginfod has been enabled.
    To make this setting permanent, add 'set debuginfod enabled on' to .gdbinit.
    Downloading 17.81 M separate debug info for /usr/bin/git
    Reading symbols from /home/mojo/.cache/debuginfod_client/9b51ee185a3310bcbbdb7373865b42b912a1b10a/debuginfo...
    [New LWP 220080]
    Downloading 1.53 M separate debug info for /usr/lib/libpcre2-8.so.0
    Downloading 194.53 K separate debug info for /usr/lib/libz.so.1
    Downloading 9.36 M separate debug info for /usr/lib/libc.so.6
    Downloading 1.07 M separate debug info for /lib64/ld-linux-x86-64.so.2
    [Thread debugging using libthread_db enabled]
    Using host libthread_db library "/usr/lib/libthread_db.so.1".
    Core was generated by `git difftool --no-symlinks --dir-diff'.
    Program terminated with signal SIGSEGV, Segmentation fault.
    Downloading 8.42 K source file /usr/src/debug/git/git-2.47.1/hashmap.c
    #0  hashmap_iter_next (iter=<synthetic pointer>) at /usr/src/debug/git/git-2.47.1/hashmap.c:299
    299iter->next = current->next;
    (gdb) bt
    #0  hashmap_iter_next (iter=<synthetic pointer>) at /usr/src/debug/git/git-2.47.1/hashmap.c:299
    #1  free_individual_entries (map=<optimized out>, entry_offset=<optimized out>) at /usr/src/debug/git/git-2.47.1/hashmap.c:183
    #2  hashmap_clear_ (map=0x7fff638c6aa0, entry_offset=<optimized out>) at /usr/src/debug/git/git-2.47.1/hashmap.c:207
    #3  0x000060193cc845c0 in hashmap_clear_ (map=0x7fff638c6aa0, entry_offset=0) at /usr/src/debug/git/git-2.47.1/hashmap.c:204
    #4  run_dir_diff (extcmd=0x0, symlinks=0, prefix=<optimized out>, child=0x7fff638c6ad0) at builtin/difftool.c:666
    #5  cmd_difftool (argc=<optimized out>, argv=<optimized out>, prefix=<optimized out>, repo=<optimized out>) at builtin/difftool.c:801
    #6  0x000060193cc2e454 in run_builtin (p=0x60193d03ed30 <commands.lto_priv+912>, argc=3, argv=0x7fff638c7990, repo=0x60193d04de20 <the_repo.lto_priv>)
        at /usr/src/debug/git/git-2.47.1/git.c:483
    #7  handle_builtin (argc=3, argv=0x7fff638c7990) at /usr/src/debug/git/git-2.47.1/git.c:749
    #8  0x000060193cc2ead9 in run_argv (argcp=0x7fff638c773c, argv=0x7fff638c7760) at /usr/src/debug/git/git-2.47.1/git.c:819
    #9  0x000060193cc297eb in cmd_main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/git/git-2.47.1/git.c:954
    #10 main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/git/git-2.47.1/common-main.c:64
    (gdb)

    Please review the rest of the bug report below.
    You can delete any lines you don't wish to share.


[System Info]
git version:
git version 2.47.1
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
libcurl: 8.11.0
OpenSSL: OpenSSL 3.4.0 22 Oct 2024
zlib: 1.3.1
uname: Linux 6.12.4-arch1-1 #1 SMP PREEMPT_DYNAMIC Mon, 09 Dec 2024 14:31:57 +0000 x86_64
compiler info: gnuc: 14.2
libc info: glibc: 2.40
$SHELL (typically, interactive shell): /bin/zsh


[Enabled Hooks]

Re: [git] bugreport of a segmentation fault

[Kristoffer Haugsbakk]

On Sun, Dec 22, 2024, at 18:23, Morten Bo Johansen wrote:
> In the attachment, I have reported a segmentation fault in git.
>
> Regards,
> Morten
>
> Attachments:
> * git-bugreport-2024-12-22-1816.txt

Hi, it looks like this was fixed in 98e40155936 (builtin/difftool:
intialize some hashmap variables, 2024-11-12).  That change will be part
of the upcoming 2.48.0 release.

It does not look like that change will be part of a maintenance release,
i.e. version 2.47.2 (based on Documentation/RelNotes/2.48.0.txt).

-- 
Kristoffer Haugsbakk