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From: Jeff King <>
To: Martin Englund <>
Cc: Philippe Blain <>,
Subject: Re: Git Bug Report: out of memory using git tag
Date: Tue, 1 Nov 2022 08:22:24 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, Oct 28, 2022 at 03:29:33PM -0700, Martin Englund wrote:

> What did you do before the bug happened? (Steps to reproduce your issue)
> I created a signed tag (git tag -s) using a ssh-agent key and then ran
> git tag -l --format '%(contents:body)' v0.6.1
> What did you expect to happen? (Expected behavior)
> I get the output
> What happened instead? (Actual behavior)
> fatal: Out of memory, malloc failed (tried to allocate
> 18446744073709551266 bytes)

Thanks for the report. This looks like pointer or size_t arithmetic that
has gone negative. Here's a minimal reproduction:

    echo subject
    echo "-----BEGIN PGP SIGNATURE-----"
  } | git tag -F - foo
  git tag -l --format='%(contents:body)' foo

The issue isn't unique to pgp signatures; the problem is in the parsing
done by ref-filter's find_subpos(), so any signature type exhibits the
problem. At the end of that function we do:

      *nonsiglen = sigstart - buf;

but "buf" has moved beyond "sigstart". Presumably because it uses
strstr() to look for end-of-line in buf. Since there isn't one before
the signature begins, we go to the end of the signature.

The bug bisects to 9f75ce3d8f (ref-filter: handle CRLF at end-of-line
more gracefully, 2020-10-29). Before then, I think our loop was careful
about moving past the start of the signature. Author cc'd.


  reply	other threads:[~2022-11-01 12:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-28 22:29 Git Bug Report: out of memory using git tag Martin Englund
2022-11-01 12:22 ` Jeff King [this message]
2022-11-02  0:41   ` Philippe Blain
2022-11-02  7:39     ` Jeff King
2022-11-02  7:42       ` [PATCH 1/2] ref-filter: fix parsing of signatures without blank lines Jeff King
2022-11-02  7:44       ` [PATCH 2/2] ref-filter: fix parsing of signatures with CRLF and no body Jeff King
2022-11-02  8:14       ` Git Bug Report: out of memory using git tag Elijah Newren
2022-11-02  9:13         ` gigantic commit messages, was " Jeff King
2022-11-02 14:26           ` Ævar Arnfjörð Bjarmason
2022-11-02 15:43             ` Elijah Newren
2022-11-02  8:24       ` Eric Sunshine
2022-11-02 12:13       ` Philippe Blain
2022-11-03  4:32         ` Jeff King
2022-11-03  0:42       ` Taylor Blau
2022-11-02  0:42   ` Philippe Blain

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