Core dump on commit

I get this error after running "git commit"

error: Object 42504431bac2e2054483c1bbc35f1b535f8d11bb is a tag, not a commit Segmentation fault (core dumped)

"git cat-file -p 42504431bac2e2054483c1bbc35f1b535f8d11bb" gives this:

object 1b9a97613307b5c7bbc189a0e41506cb1534740a type commit tag v1.0 tagger marko <marko@bib> Sun Aug 14 20:42:12 2011 -0400

The first release

I had created a tag yesterday which I deleted since with "git tag -d" command.

Curiously, I could not find file ".git/objects/42/504431bac2e2054483c1bbc35f1b535f8d11bb" which I expected based on my very limited understanding of the Git internals. So, where does "git cat-file" pick up that information from? But more importantly, how do I fix this problem?

On Mon, Aug 15, 2011 at 14:30, Marko Vukovic <amasniko@yahoo.com> wrote:

You found a SHA-1 hash collision!? :-P (but really :-/)

Michael Witten <mfwitten <at> gmail.com> writes:

Do I go out and buy a lottery ticket now?

But seriously, how do I get out of this mess now?

On Mon, Aug 15, 2011 at 9:30 PM, Marko Vukovic <amasniko@yahoo.com> wrote:

Can you get the stack trace? Does HEAD point to 42504431bac2e2054483c1bbc35f1b535f8d11bb (iow what does "git rev-parse HEAD" say).

If HEAD does point to 42504431, I think you can do "git reset 1b9a976133" to reset the HEAD back to a commit object (as oppose to a tag)

But please backup the repository somewhere, I'm still not sure how you get into this situation. The repo may help. -- Duy

Nguyen Thai Ngoc Duy <pclouds <at> gmail.com> writes:

Please find the stack trace at the end of the message (I did not want to insert it in the middle)

It does print the same hash.

Pardon my ignorance, but what does "git reset" do? I have got some uncommitted changes in the staging area. What will happen to them?

The stack trace:

[New Thread 10518]
[Thread debugging using libthread_db enabled]
Core was generated by `git commit'.
Program terminated with signal 11, Segmentation fault.
#0  sha1_to_hex (sha1=0x4 <Address 0x4 out of bounds>) at hex.c:60
60      hex.c: No such file or directory.
        in hex.c

Thread 1 (Thread 0x7f290c8e3720 (LWP 10518)):
#0  sha1_to_hex (sha1=0x4 <Address 0x4 out of bounds>) at hex.c:60
        val = <value optimized out>
        bufno = 3
        hexbuffer = {'\000' <repeats 49 times>,
"42504431bac2e2054483c1bbc35f1b535f8d11bb\000\000\000\000\000\000\000\000\000",
"583438f1bd3bf58f3defb0cb6adbf32b26a2ce43\000\000\000\000\000\000\000\000\000",
'\000' <repeats 49 times>}
        hex = "0123456789abcdef"
        buffer = 0x75f936 ""
#1  0x0000000000471fe3 in commit_tree (msg=0x9d5920 "Weekend and holiday
fees\n", tree=<value optimized out>, parents=0x9d5900, ret=0x7fff55c683f0
"\022", author=0x989f10 "Marko Vukovic <marko@bib.(none)> 1313422327 -0400") at
commit.c:855
        next = 0x0
        result = <value optimized out>
        encoding_is_utf8 = 1
        buffer = {alloc = 8193, len = 46, buf = 0x9d8950 "tree
583438f1bd3bf58f3defb0cb6adbf32b26a2ce43\n"}
#2  0x000000000041c223 in cmd_commit (argc=<value optimized out>, argv=<value
optimized out>, prefix=0x0) at builtin/commit.c:1394
        sb = {alloc = 12313, len = 25, buf = 0x9d5920 "Weekend and holiday fees\

n"}
        author_ident = {alloc = 50, len = 49, buf = 0x989f10 "Marko Vukovic
<marko@bib.(none)> 1313422327 -0400"}
        index_file = 0x7fff55c67330 ""
        reflog_msg = 0x4e6e0f "commit"
        nl = <value optimized out>
        p = <value optimized out>
        commit_sha1 =
"\022\000\000\000\000\000\000\000\022\000\000\000\000\000\000\000[\000\000"
        ref_lock = <value optimized out>
        parents = 0x9d5900
        pptr = <value optimized out>
        statbuf = {st_dev = 0, st_ino = 2, st_nlink = 0, st_mode = 0, st_uid =
0, st_gid = 1439068784, __pad0 = 32767, st_rdev = 64, st_size = 0, st_blksize =
0, st_blocks = 0, st_atim = {tv_sec = 206158430210, tv_nsec = 472446402651},
st_mtim = {tv_sec = 532575944823, tv_nsec = 140734632456832}, st_ctim = {tv_sec
= 140734632456815, tv_nsec = 140734632457008}, __unused = {4096, 5116818,
233337090496}}
        s = {is_initial = 0, branch = 0x9754c0 "refs/heads/release-1", reference

= 0x4e3c11 "HEAD", pathspec = 0x0, verbose = 0, amend = 0, in_merge = 0, nowarn
= 1, use_color = 0, relative_paths = 1, submodule_summary = 0,
show_ignored_files = 0, show_untracked_files = SHOW_NORMAL_UNTRACKED_FILES,
ignore_submodule_arg = 0x0, color_palette = {'\000' <repeats 39 times>,
"\033[32m", '\000' <repeats 34 times>, "\033[31m", '\000' <repeats 34 times>,
"\033[31m", '\000' <repeats 34 times>, "\033[31m", '\000' <repeats 34 times>,
"\033[31m", '\000' <repeats 34 times>, "\033[32m", '\000' <repeats 34 times>,
"\033[31m", '\000' <repeats 34 times>, "NIL", '\000' <repeats 36 times>},
commitable = 1, workdir_dirty = 1, index_file = 0x975480 ".git/index", fp =
0x988630, prefix = 0x0, change = {items = 0x98ae60, nr = 10, alloc = 32,
strdup_strings = 1}, untracked = {items = 0x9cd490, nr = 14, alloc = 32,
strdup_strings = 1}, ignored = {items = 0x0, nr = 0, alloc = 0, strdup_strings =
 1}}
#3  0x000000000040462c in run_builtin (argc=1, argv=0x7fff55c686a0) at git.c:290

        status = <value optimized out>
        help = <value optimized out>
        st = {st_dev = 7094065766045672051, st_ino = 7308620263551823465,
st_nlink = 7074996046893509935, st_mode = 28265, st_uid = 0, st_gid = 9916512,
__pad0 = 0, st_rdev = 233333546946, st_size = 140734632462224, st_blksize = 1,
st_blocks = 4294967296, st_atim = {tv_sec = 150, tv_nsec = 9916512}, st_mtim =
{tv_sec = 140734632461552, tv_nsec = 140734632471472}, st_ctim = {tv_sec =
4210352, tv_nsec = 140734632461648}, __unused = {0, 0, 4992233}}
        prefix = <value optimized out>
#4  handle_internal_command (argc=1, argv=0x7fff55c686a0) at git.c:448
        p = <value optimized out>
        cmd = <value optimized out>
        commands = {{cmd = 0x4f481b "add", fn = 0x4051d0 <cmd_add>, option = 9},

{cmd = 0x4e1145 "stage", fn = 0x4051d0 <cmd_add>, option = 9}, {cmd = 0x4e114b "annotate", fn = 0x405bf0 <cmd_annotate>, option = 1}, {cmd = 0x4e1949 "apply", fn = 0x40c9e0 <cmd_apply>, option = 2}, {cmd = 0x4e3426 "archive", fn = 0x40d6d0

<cmd_archive>, option = 0}, {cmd = 0x4e1154 "bisect--helper", fn = 0x40d940 <cmd_bisect__helper>, option = 9}, {cmd = 0x4e1163 "blame", fn = 0x410210 <cmd_blame>, option = 1}, {cmd = 0x4f49e0 "branch", fn = 0x412a00 <cmd_branch>, option = 1}, {cmd = 0x4e6363 "bundle", fn = 0x413b30 <cmd_bundle>, option = 2}, {cmd = 0x4e1169 "cat-file", fn = 0x413e30 <cmd_cat_file>, option = 1}, {cmd = 0x4e649d "checkout", fn = 0x4168e0 <cmd_checkout>, option = 9}, {cmd = 0x4e1172 "checkout-index", fn = 0x4150c0 <cmd_checkout_index>, option = 9}, {cmd = 0x4e1181 "check-ref-format", fn = 0x414b20 <cmd_check_ref_format>, option = 0}, {cmd = 0x4e1192 "check-attr", fn = 0x4147b0 <cmd_check_attr>, option = 1}, {cmd = 0x4e119d "cherry", fn = 0x4360c0 <cmd_cherry>, option = 1}, {cmd = 0x50432a "cherry-pick", fn = 0x45a1a0 <cmd_cherry_pick>, option = 9}, {cmd = 0x4e11a4 "clone", fn = 0x418d30 <cmd_clone>, option = 0}, {cmd = 0x4e11aa "clean", fn = 0x417fa0 <cmd_clean>, option = 9}, {cmd = 0x4e6e0f "commit", fn = 0x41b2b0 <cmd_commit>, option = 9}, {cmd = 0x4e11b0 "commit-tree", fn = 0x419f80 <cmd_commit_tree>, option = 1}, {cmd = 0x4e1392 "config", fn = 0x41e010 <cmd_config>, option = 2}, {cmd = 0x4e11bc "count-objects", fn = 0x41e740 <cmd_count_objects>, option = 1}, {cmd = 0x4e11ca "describe", fn = 0x41f8f0 <cmd_describe>, option = 1}, {cmd = 0x4fd07d "diff", fn = 0x420910 <cmd_diff>, option = 0}, {cmd = 0x4e11d3 "diff-files", fn = 0x41fe80 <cmd_diff_files>, option = 9}, {cmd = 0x4e11de "diff-index", fn = 0x4200d0 <cmd_diff_index>, option = 1}, {cmd = 0x4e11e9 "diff-tree", fn = 0x420270 <cmd_diff_tree>, option = 1}, {cmd = 0x506d5a "fast-export", fn = 0x421d20 <cmd_fast_export>, option = 1}, {cmd = 0x4e63e3 "fetch", fn = 0x426a70 <cmd_fetch>, option = 1}, {cmd = 0x4e11f3 "fetch-pack", fn = 0x4245e0 <cmd_fetch_pack>, option = 1}, {cmd = 0x4e11fe "fmt-merge-msg", fn = 0x427a20 <cmd_fmt_merge_msg>, option = 1}, {cmd =

0x4e120c "for-each-ref", fn = 0x4296b0 <cmd_for_each_ref>, option = 1}, {cmd = 0x4e1219 "format-patch", fn = 0x434930 <cmd_format_patch>, option = 1}, {cmd = 0x4fe34e "fsck", fn = 0x42a910 <cmd_fsck>, option = 1}, {cmd = 0x4e1226 "fsck-objects", fn = 0x42a910 <cmd_fsck>, option = 1}, {cmd = 0x4ebe68 "gc", fn = 0x42b490 <cmd_gc>, option = 1}, {cmd = 0x4e1233 "get-tar-commit-id", fn = 0x460a10 <cmd_get_tar_commit_id>, option = 0}, {cmd = 0x4ec25b "grep", fn = 0x42cbe0 <cmd_grep>, option = 2}, {cmd = 0x4e1245 "hash-object", fn = 0x42e540 <cmd_hash_object>, option = 0}, {cmd = 0x4e0f80 "help", fn = 0x42f210 <cmd_help>, option = 0}, {cmd = 0x4e1251 "index-pack", fn = 0x4307c0 <cmd_index_pack>, option = 2}, {cmd = 0x4e6527 "init", fn = 0x432920 <cmd_init_db>, option = 0}, {cmd = 0x4e125c "init-db", fn = 0x432920 <cmd_init_db>, option = 0}, {cmd = 0x503888 "log", fn = 0x434850 <cmd_log>, option = 1}, {cmd = 0x4e1264 "ls-files", fn = 0x436bc0 <cmd_ls_files>, option = 1}, {cmd = 0x4e126d "ls-tree", fn = 0x438560 <cmd_ls_tree>, option = 1}, {cmd = 0x4e1275 "ls-remote", fn = 0x437e20 <cmd_ls_remote>, option = 2}, {cmd = 0x4e127f "mailinfo", fn = 0x439fb0 <cmd_mailinfo>, option = 0}, {cmd = 0x4e1288 "mailsplit", fn = 0x43b4d0 <cmd_mailsplit>, option = 0}, {cmd = 0x4f01d7 "merge", fn = 0x43d170 <cmd_merge>, option = 9}, {cmd = 0x4e1292 "merge-base", fn = 0x43ece0 <cmd_merge_base>, option = 1}, {cmd = 0x4e129d "merge-file", fn = 0x43f060 <cmd_merge_file>, option = 2}, {cmd = 0x4e12a8 "merge-index", fn = 0x43f820 <cmd_merge_index>, option = 1}, {cmd = 0x4e12b4 "merge-ours", fn = 0x43fa50 <cmd_merge_ours>, option = 1}, {cmd = 0x4e12bf "merge-recursive", fn = 0x43fb20 <cmd_merge_recursive>, option = 9}, {cmd = 0x4e12cf "merge-recursive-ours", fn = 0x43fb20 <cmd_merge_recursive>, option = 9}, {cmd =

0x4e12e4 "merge-recursive-theirs", fn = 0x43fb20 <cmd_merge_recursive>, option =

9}, {cmd = 0x4e12fb "merge-subtree", fn = 0x43fb20 <cmd_merge_recursive>, option

= 9}, {cmd = 0x4e1309 "merge-tree", fn = 0x440340 <cmd_merge_tree>, option = 1},

{cmd = 0x4e1314 "mktag", fn = 0x440710 <cmd_mktag>, option = 1}, {cmd = 0x4e131a

"mktree", fn = 0x440c70 <cmd_mktree>, option = 1}, {cmd = 0x4e1321 "mv", fn = 0x441450 <cmd_mv>, option = 9}, {cmd = 0x4e1324 "name-rev", fn = 0x4421c0 <cmd_name_rev>, option = 1}, {cmd = 0x4f108c "notes", fn = 0x443880 <cmd_notes>,

option = 1}, {cmd = 0x4fad16 "pack-objects", fn = 0x448240 <cmd_pack_objects>, option = 1}, {cmd = 0x4e132d "pack-redundant", fn = 0x449b70 <cmd_pack_redundant>, option = 1}, {cmd = 0x4e133c "patch-id", fn = 0x44b100 <cmd_patch_id>, option = 0}, {cmd = 0x4e1345 "peek-remote", fn = 0x437e20 <cmd_ls_remote>, option = 2}, {cmd = 0x4e1351 "pickaxe", fn = 0x410210 <cmd_blame>, option = 1}, {cmd = 0x4f4757 "prune", fn = 0x44b750 <cmd_prune>, option = 1}, {cmd = 0x4e1359 "prune-packed", fn = 0x44b520 <cmd_prune_packed>, option = 1}, {cmd = 0x506773 "push", fn = 0x44bdd0 <cmd_push>, option = 1}, {cmd = 0x4e1366 "read-tree", fn = 0x44c8d0 <cmd_read_tree>, option = 1}, {cmd = 0x4f6fcf "receive-pack", fn = 0x44da50 <cmd_receive_pack>, option = 0}, {cmd = 0x4e4514 "reflog", fn = 0x4503f0 <cmd_reflog>, option = 1}, {cmd = 0x4f4614 "remote", fn = 0x4519a0 <cmd_remote>, option = 1}, {cmd = 0x4e1370 "remote-ext",

fn = 0x454c20 <cmd_remote_ext>, option = 0}, {cmd = 0x4e137b "remote-fd", fn = 0x454dd0 <cmd_remote_fd>, option = 0}, {cmd = 0x4e1385 "replace", fn = 0x4551f0 <cmd_replace>, option = 1}, {cmd = 0x4e138d "repo-config", fn = 0x41e010 <cmd_config>, option = 2}, {cmd = 0x4e1399 "rerere", fn = 0x455540 <cmd_rerere>,

option = 1}, {cmd = 0x4e5743 "reset", fn = 0x455ff0 <cmd_reset>, option = 1}, {cmd = 0x4eaa47 "rev-list", fn = 0x456f30 <cmd_rev_list>, option = 1}, {cmd = 0x4e13a0 "rev-parse", fn = 0x457930 <cmd_rev_parse>, option = 0}, {cmd = 0x4e13aa "revert", fn = 0x45a150 <cmd_revert>, option = 9}, {cmd = 0x4e13b1 "rm", fn = 0x45a1b0 <cmd_rm>, option = 1}, {cmd = 0x4e13b4 "send-pack", fn = 0x45b3d0 <cmd_send_pack>, option = 1}, {cmd = 0x4e13be "shortlog", fn = 0x45c640

<cmd_shortlog>, option = 6}, {cmd = 0x4e13c7 "show-branch", fn = 0x45d2f0 <cmd_show_branch>, option = 1}, {cmd = 0x4e13d3 "show", fn = 0x434390 <cmd_show>, option = 1}, {cmd = 0x4f6f44 "status", fn = 0x41b000 <cmd_status>, option = 9}, {cmd = 0x4e13d8 "stripspace", fn = 0x45f170 <cmd_stripspace>, option = 0}, {cmd = 0x4e13e3 "symbolic-ref", fn = 0x45f260 <cmd_symbolic_ref>, option = 1}, {cmd = 0x50640d "tag", fn = 0x45f9a0 <cmd_tag>, option = 1}, {cmd =

0x4e13f0 "tar-tree", fn = 0x460880 <cmd_tar_tree>, option = 0}, {cmd = 0x4e13f9 "unpack-file", fn = 0x460af0 <cmd_unpack_file>, option = 1}, {cmd = 0x4e1405 "unpack-objects", fn = 0x461510 <cmd_unpack_objects>, option = 1}, {cmd = 0x4e1414 "update-index", fn = 0x463550 <cmd_update_index>, option = 1}, {cmd = 0x4e1421 "update-ref", fn = 0x464150 <cmd_update_ref>, option = 1}, {cmd = 0x4e142c "update-server-info", fn = 0x4643e0 <cmd_update_server_info>, option = 1}, {cmd = 0x4e341f "upload-archive", fn = 0x4647e0 <cmd_upload_archive>, option

= 0}, {cmd = 0x4e143f "var", fn = 0x464ac0 <cmd_var>, option = 2}, {cmd =
0x4e1443 "verify-tag", fn = 0x4653b0 <cmd_verify_tag>, option = 1}, {cmd =
0x50005d "version", fn = 0x48ebd0 <cmd_version>, option = 0}, {cmd = 0x4e144e
"whatchanged", fn = 0x434280 <cmd_whatchanged>, option = 1}, {cmd = 0x4f9c35
"write-tree", fn = 0x4655c0 <cmd_write_tree>, option = 1}, {cmd = 0x4e145a
"verify-pack", fn = 0x465090 <cmd_verify_pack>, option = 0}, {cmd = 0x4e1466
"show-ref", fn = 0x45ed70 <cmd_show_ref>, option = 1}, {cmd = 0x4e146f
"pack-refs", fn = 0x44ac80 <cmd_pack_refs>, option = 1}}
        i = <value optimized out>
#5  0x0000000000404848 in run_argv (argc=1, argv=0x7fff55c686a0) at git.c:492
        done_alias = 0
#6  main (argc=1, argv=0x7fff55c686a0) at git.c:565
        done_help = 0
        was_alias = 0
        cmd = 0x7fff55c6a2dc "commit"
From                To                  Syms Read   Shared Object Library
0x0000003cb5c01e70  0x0000003cb5c0e678  Yes         /lib64/libz.so.1
0x0000003654805630  0x00000036548108b8  Yes (*)     /lib64/libpthread.so.0
0x0000003653c1eba0  0x0000003653d45f5c  Yes (*)     /lib64/libc.so.6
0x0000003653800b20  0x0000003653818c46  Yes (*)     /lib64/ld-linux-x86-64.so.2
0x00007f290c6d9120  0x00007f290c6e0448  Yes (*)     /lib64/libnss_files.so.2
(*): Shared library is missing debugging information.
$1 = 0x0
No symbol "__glib_assert_msg" in current context.
rax            0x75f936 7731510
rbx            0x9d5900 10311936
rcx            0x4fb256 5222998
rdx            0x0      0
rsi            0x2e     46
rdi            0x4      4
rbp            0x0      0x0
rsp            0x7fff55c66e88   0x7fff55c66e88
r8             0x1      1
r9             0x28     40
r10            0x3261363262323366       3630242364661052262
r11            0x2001   8193
r12            0x9d5920 10311968
r13            0x7fff55c683f0   140734632461296
r14            0x7fff55c66ea0   140734632455840
r15            0x989f10 10002192
rip            0x48ec78 0x48ec78 <sha1_to_hex+40>
eflags         0x10206  [ PF IF RF ]
cs             0x33     51
ss             0x2b     43
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0
Dump of assembler code for function sha1_to_hex:
   0x000000000048ec50 <+0>:     mov    0x2d0d12(%rip),%eax        # 0x75f968
   0x000000000048ec56 <+6>:     xor    %edx,%edx
   0x000000000048ec58 <+8>:     add    $0x1,%eax
   0x000000000048ec5b <+11>:    mov    %eax,0x2d0d07(%rip)        # 0x75f968
   0x000000000048ec61 <+17>:    and    $0x3,%eax
   0x000000000048ec64 <+20>:    lea    (%rax,%rax,4),%rax
   0x000000000048ec68 <+24>:    lea    (%rax,%rax,4),%rax
   0x000000000048ec6c <+28>:    lea    0x75f8a0(%rax,%rax,1),%rax
   0x000000000048ec74 <+36>:    nopl   0x0(%rax)
=> 0x000000000048ec78 <+40>:    movzbl (%rdi),%ecx
   0x000000000048ec7b <+43>:    add    $0x1,%rdi
   0x000000000048ec7f <+47>:    mov    %ecx,%esi
   0x000000000048ec81 <+49>:    and    $0xf,%ecx
   0x000000000048ec84 <+52>:    shr    $0x4,%esi
   0x000000000048ec87 <+55>:    movzbl 0x4fec80(%rcx),%ecx
   0x000000000048ec8e <+62>:    mov    %esi,%esi
   0x000000000048ec90 <+64>:    movzbl 0x4fec80(%rsi),%esi
   0x000000000048ec97 <+71>:    mov    %cl,0x1(%rax,%rdx,1)
   0x000000000048ec9b <+75>:    mov    %sil,(%rax,%rdx,1)
   0x000000000048ec9f <+79>:    add    $0x2,%rdx
   0x000000000048eca3 <+83>:    cmp    $0x28,%rdx
   0x000000000048eca7 <+87>:    jne    0x48ec78 <sha1_to_hex+40>
   0x000000000048eca9 <+89>:    movb   $0x0,0x28(%rax)
   0x000000000048ecad <+93>:    retq
End of assembler dump.

On Mon, Aug 15, 2011 at 10:48 PM, Marko Vukovic <amasniko@yahoo.com> wrote:

I should have written "git reset --soft 1b9a976133", which resets HEAD ref back to (assuming) good commit. See [1] for more information. I think for some reason, eGit put a tag object to HEAD, while it should be a commit object. By resetting it back to the commit that the tag points to, you may be able to commit again.

No history would be lost. Also if you use --soft, index should be untouched. As always, back up your repository (copy the whole directory, including .git) before doing anything.

[1] http://www.kernel.org/pub/software/scm/git/docs/git-reset.html

Nguyen Thai Ngoc Duy <pclouds <at> gmail.com> writes:

Thank you very much, I was able to commit after the reset.

I shall remember never to use eGit for tagging in the future!

On Mon, 2011-08-15 at 16:09 +0000, Marko Vukovic wrote:

A (probably) more useful way to deal with it would be to report a bug to EGIT so they know about it and can fix it.

Cheers,
   cmn

On Mon, Aug 15, 2011 at 9:30 PM, Marko Vukovic <amasniko@yahoo.com> wrote:

If I put a tag to HEAD, I could reproduce this. Let's assume that "git cat-file -t HEAD" in your repo returns "tag", how did you create the last commits? Did you modify a ref manually? What git version did you use?

Nguyen Thai Ngoc Duy <pclouds <at> gmail.com> writes:

Sorry, I do not understand what you mean by "modifying a ref manually". I created the last commit and the tag with the Eclipse plugin "eGit". Later when I could not create more commits, I deleted the tag from the command line and also tried to commit from the command line which gave me the core dump.

I have got git.x86_64 package 1.7.4.4-1.fc14 installed on my computer.