git/list[1] front-page[2] threads[3] people[4] search[5] about
 

Re: Segfault in git reflog

From
Duy Nguyen <pclouds@gmail.com>
Date
Dec 30, 2015, 11:26 UTC
Message-ID
<CACsJy8CoRs8dNPWag-E947oVTt4R8XbKBLvaQvBPGm4jqZBKNw@mail.gmail.com>
In-Reply-To
<1451474248.9251.7.camel@kaarsemaker.net>

On Wed, Dec 30, 2015 at 6:17 PM, Dennis Kaarsemaker <dennis@kaarsemaker.net> wrote:

Show 8 quoted lines
> On wo, 2015-12-30 at 10:24 +0100, Dennis Kaarsemaker wrote:
>> spirit:~/code/git (master)$ cat .git/logs/HEAD
>> 2635c2b8bfc9aec07b7f023d8e3b3d02df715344 54bc41416c5d3ecb978acb0df80d57aa3e54494c Dennis Kaarsemaker <dennis@kaarsemaker.net> 1446765642 +0100
>> 74c855f87d25a5b5c12d0485ec77c785a1c734c5 54bc41416c5d3ecb978acb0df80d57aa3e54494c Dennis Kaarsemaker <dennis@kaarsemaker.net> 1446765951 +0100  checkout: moving from 3c3d3f629a6176b401ebec455c5dd59ed1b5f910 to master
>
> 74c855f87d25a5b5c12d0485ec77c785a1c734c5 is actually a tag, pointing to
> 3c3d3f629a6176b401ebec455c5dd59ed1b5f910. I'm not sure if that is
> relevant.

It is. save_parents() expects "commit" to be a commit because it needs commit->index, which is not available from struct tag. So when saved_parents_at() tries to read commit->index, it gets random value (from the tag). Hell breaks loose from there because this index field points to some memory in the slab mem allocator. The question is, how come a tag is passed in here. Maybe we can sprinkle some assert(object->type == OBJ_COMMIT) in revision.c and see..

-- 
Duy
Previous: Dennis KaarsemakerNext: Duy Nguyen
Message 4 of 25 in “Segfault in git reflog”
  1. Dennis KaarsemakerDec 30, 2015
  2. Duy NguyenDec 30, 2015
  3. Dennis KaarsemakerDec 30, 2015
  4. Duy NguyenDec 30, 2015
  5. Duy NguyenDec 30, 2015
  6. Dennis KaarsemakerDec 30, 2015
  7. Duy NguyenDec 30, 2015
  8. reflog-walk: don't segfault on non-commit sha1's in the reflogDennis Kaarsemaker, Dec 30, 2015
  9. Junio C HamanoDec 30, 2015
  10. Dennis KaarsemakerDec 30, 2015
  11. Junio C HamanoDec 30, 2015
  12. Dennis KaarsemakerDec 30, 2015
  13. reflog-walk: don't segfault on non-commit sha1's in the reflogDennis Kaarsemaker, Dec 30, 2015
  14. Junio C HamanoDec 30, 2015
  15. reflog-walk: don't segfault on non-commit sha1's in the reflogDennis Kaarsemaker, Dec 30, 2015
  16. Junio C HamanoDec 31, 2015
  17. Dennis KaarsemakerDec 31, 2015
  18. Dennis KaarsemakerDec 31, 2015
  19. reflog-walk: don't segfault on non-commit sha1's in the reflogDennis Kaarsemaker, Jan 5, 2016
  20. Eric SunshineJan 6, 2016
  21. Dennis KaarsemakerJan 6, 2016
  22. Eric SunshineJan 6, 2016
  23. Eric SunshineJan 6, 2016
  24. Dennis KaarsemakerJan 6, 2016
  25. Duy NguyenJan 6, 2016

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.