[PATCH 07/15] get_sha1_with_context: always initialize oc->symlink_path
- From
Jeff King <peff@peff.net>
- Date
- May 19, 2017, 12:52 UTC
- Message-ID
- <20170519125224.gnfifzcyly2n5te6@sigill.intra.peff.net>
- In-Reply-To
- <20170519124651.4q7waz75rmzfopgn@sigill.intra.peff.net>
The get_sha1_with_context() function zeroes out the oc->symlink_path strbuf, but doesn't use strbuf_init() to set up the usual invariants (like pointing to the slopbuf). We don't actually write to the oc->symlink_path strbuf unless we call get_tree_entry_follow_symlinks(), and that function does initialize it. However, readers may still look at the zero'd strbuf.
In practice this isn't a triggerable bug. The only caller that looks at it only does so when the mode we found is 0. This doesn't happen for non-tree-entries (where we return S_IFINVALID). A broken tree entry could have a mode of 0, but canon_mode() quietly rewrites that into S_IFGITLINK. So the "0" mode should only come up when we did indeed find a symlink.
This is mostly just an accident of how the code happens to work, though. Let's future-proof ourselves to make sure the strbuf is properly initialized for all calls (it's only a few struct member assignments, not a heap allocation).
Signed-off-by: Jeff King <peff@peff.net> --- sha1_name.c | 1 + tree-walk.c | 1 - 2 files changed, 1 insertion(+), 1 deletion(-)
diff --git a/sha1_name.c b/sha1_name.c index a11d08dd8..35b16efc6 100644 --- a/sha1_name.c +++ b/sha1_name.c @@ -1511,6 +1511,7 @@ static int get_sha1_with_context_1(const char *name, memset(oc, 0, sizeof(*oc)); oc->mode = S_IFINVALID; + strbuf_init(&oc->symlink_path, 0); ret = get_sha1_1(name, namelen, sha1, flags); if (!ret) return ret; diff --git a/tree-walk.c b/tree-walk.c index ff7760568..c7ecfc856 100644 --- a/tree-walk.c +++ b/tree-walk.c @@ -589,7 +589,6 @@ enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_s int i; init_tree_desc(&t, NULL, 0UL); - strbuf_init(result_path, 0); strbuf_addstr(&namebuf, name); hashcpy(current_tree_sha1, tree_sha1);
-- 2.13.0.219.g63f6bc368