[PATCH v3 05/25] refs: prevent accidental NULL dereference in write_pseudoref

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Oct 15, 2017, 22:06 UTC
Message-ID: <20171015220712.97308-6-sandals@crustytoothpaste.net>
In-Reply-To: <20171015220712.97308-1-sandals@crustytoothpaste.net>

Several of the refs functions take NULL to indicate that the ref is not to be updated. If refs_update_ref were called with a NULL new object ID, we could pass that NULL pointer to write_pseudoref, which would then segfault when it dereferenced it. Instead, simply return successfully, since if we don't want to update the pseudoref, there's nothing to do.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 refs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/refs.c b/refs.c
index edd20044c6..91c2af78b6 100644
--- a/refs.c
+++ b/refs.c
@@ -583,6 +583,9 @@ static int write_pseudoref(const char *pseudoref, const struct object_id *oid,
 	struct strbuf buf = STRBUF_INIT;
 	int ret = -1;
 
+	if (!oid)
+		return 0;
+
 	strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
 
 	filename = git_path("%s", pseudoref);

-- 
2.15.0.rc0.271.g36b669edcc