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Copy resolve_ref() return value for longer use

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resolve_ref() may return a pointer to a static buffer. Callers that
use this value longer than a couple of statements should copy the
value to avoid some hidden resolve_ref() call that may change the
static buffer's value.

The bug found by Tony Wang <wwwjfy@gmail.com> in builtin/merge.c
demonstrates this. The first call is in cmd_merge()

branch = resolve_ref("HEAD", head_sha1, 0, &flag);

Then deep in lookup_commit_or_die() a few lines after, resolve_ref()
may be called again and destroy "branch".

lookup_commit_or_die
 lookup_commit_reference
  lookup_commit_reference_gently
   parse_object
    lookup_replace_object
     do_lookup_replace_object
      prepare_replace_object
       for_each_replace_ref
        do_for_each_ref
         get_loose_refs
          get_ref_dir
           get_ref_dir
            resolve_ref

All call sites are checked and made sure that xstrdup() is called if
the value should be saved.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nguyễn Thái Ngọc Duy
2011-11-13 17:22:15 +07:00
committed by Junio C Hamano
parent c689332391
commit d5a35c114a
8 changed files with 66 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
builtin/notes.c
View File

@ -804,6 +804,7 @@ static int merge_commit(struct notes_merge_options *o)
struct notes_tree *t;
struct commit *partial;
struct pretty_print_context pretty_ctx;
int ret;
/*
* Read partial merge result from .git/NOTES_MERGE_PARTIAL,
@ -828,6 +829,7 @@ static int merge_commit(struct notes_merge_options *o)
o->local_ref = resolve_ref("NOTES_MERGE_REF", sha1, 0, NULL);
if (!o->local_ref)
die("Failed to resolve NOTES_MERGE_REF");
o->local_ref = xstrdup(o->local_ref);
if (notes_merge_commit(o, t, partial, sha1))
die("Failed to finalize notes merge");
@ -843,7 +845,9 @@ static int merge_commit(struct notes_merge_options *o)
free_notes(t);
strbuf_release(&msg);
return merge_abort(o);
ret = merge_abort(o);
free((char *)o->local_ref);
return ret;
}
static int merge(int argc, const char **argv, const char *prefix)