From: René Scharfe <l.s.r@web.de>
Date: Sat, 6 May 2017 17:13:52 +0000 (+0200)
Subject: checkout: check return value of resolve_refdup before using hash
X-Git-Tag: v2.13.1~18^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=79e913c24aa37d0ede9ed9e8962a19634ae5129a;p=thirdparty%2Fgit.git

checkout: check return value of resolve_refdup before using hash

If resolve_refdup() fails it returns NULL and possibly leaves its hash
output parameter untouched.  Make sure to use it only if the function
succeeded, in order to avoid accessing uninitialized memory.

Found with t/t2011-checkout-invalid-head.sh --valgrind.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 81f07c3ef2..5744499098 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -814,7 +814,8 @@ static int switch_branches(const struct checkout_opts *opts,
 	int flag, writeout_error = 0;
 	memset(&old, 0, sizeof(old));
 	old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
-	old.commit = lookup_commit_reference_gently(rev.hash, 1);
+	if (old.path)
+		old.commit = lookup_commit_reference_gently(rev.hash, 1);
 	if (!(flag & REF_ISSYMREF))
 		old.path = NULL;