From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 8 Mar 2018 20:36:26 +0000 (-0800)
Subject: Merge branch 'ds/find-unique-abbrev-optim'
X-Git-Tag: v2.17.0-rc0~26
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/7519a60ffa3f811ec49fd9956e284ff90f3b1cf1?hp=65ebfec5154c32e60efbec318e23110a1660809c

Merge branch 'ds/find-unique-abbrev-optim'

While finding unique object name abbreviation, the code may
accidentally have read beyond the end of the array of object names
in a pack.

* ds/find-unique-abbrev-optim:
sha1_name: fix uninitialized memory errors
---

diff --git a/sha1_name.c b/sha1_name.c
index e7c18ffc26..735c1c0b8e 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -542,20 +542,20 @@ static void find_abbrev_len_for_pack(struct packed_git *p,
 	/*
 	 * first is now the position in the packfile where we would insert
 	 * mad->hash if it does not exist (or the position of mad->hash if
-	 * it does exist). Hence, we consider a maximum of three objects
+	 * it does exist). Hence, we consider a maximum of two objects
 	 * nearby for the abbreviation length.
 	 */
 	mad->init_len = 0;
 	if (!match) {
-		nth_packed_object_oid(&oid, p, first);
-		extend_abbrev_len(&oid, mad);
+		if (nth_packed_object_oid(&oid, p, first))
+			extend_abbrev_len(&oid, mad);
 	} else if (first < num - 1) {
-		nth_packed_object_oid(&oid, p, first + 1);
-		extend_abbrev_len(&oid, mad);
+		if (nth_packed_object_oid(&oid, p, first + 1))
+			extend_abbrev_len(&oid, mad);
 	}
 	if (first > 0) {
-		nth_packed_object_oid(&oid, p, first - 1);
-		extend_abbrev_len(&oid, mad);
+		if (nth_packed_object_oid(&oid, p, first - 1))
+			extend_abbrev_len(&oid, mad);
 	}
 	mad->init_len = mad->cur_len;
 }