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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

5
builtin/branch.c
View File

@ -115,8 +115,10 @@ static int branch_merged(int kind, const char *name,
branch->merge[0] &&
branch->merge[0]->dst &&
(reference_name =
resolve_ref(branch->merge[0]->dst, sha1, 1, NULL)) != NULL)
resolve_ref(branch->merge[0]->dst, sha1, 1, NULL)) != NULL) {
reference_name = xstrdup(reference_name);
reference_rev = lookup_commit_reference(sha1);
}
}
if (!reference_rev)
reference_rev = head_rev;
@ -141,6 +143,7 @@ static int branch_merged(int kind, const char *name,
" '%s', even though it is merged to HEAD."),
name, reference_name);
}
free((char *)reference_name);
return merged;
}