On Wed, May 02, 2012 at 02:53:22PM +0200, René Scharfe wrote:
> [cc:ing the author of this commit]
>
> Am 02.05.2012 10:45, schrieb Michael Mueller:
> >Hi all,
> >
> >The last defect Sentry picked up has been removed, yay! At the same
> >time, a new NULL dereference bug appeared, in sequencer.c:
> >
> > static int is_index_unchanged(void)
> > {
> > unsigned char head_sha1[20];
> > struct commit *head_commit;
> >
> > if (!resolve_ref_unsafe("HEAD", head_sha1, 1, NULL))
> > return error(_("Could not resolve HEAD commit\n"));
> >
> > head_commit = lookup_commit(head_sha1);
> > if (!head_commit || parse_commit(head_commit))
> > return error(_("could not parse commit %s\n"),
> > sha1_to_hex(head_commit->object.sha1));
> >
> >In the last line quoted above, head_commit may be NULL, and it is
> >dereferenced in the call to sha1_to_hex. Assuming lookup_commit(head_sha1)
> >can return NULL, this function will segfault.
> >
> >Introduced here:
> >https://github.com/gitster/git/commit/b27cfb0#sequencer.c
>
> Similar code in builtin/commit.c just reports "could not parse HEAD
> commit" without any hash and thus no pointer dereference.
>
> René
>
Have you actually seen this problem occur? It seems to me that the only way
head_commit could be NULL is in the event that HEAD wasn't a commit object,
whcih I don't think can be the case unless something else is very wrong with
your tree.
Neil
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