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[PATCH] sha1_name: fix uninitialized memory errors

From
Derrick Stolee <dstolee@microsoft.com>
Date
Feb 26, 2018, 14:56 UTC
Message-ID
<1519657007-215623-1-git-send-email-dstolee@microsoft.com>
In-Reply-To
<CAP8UFD0CesVk8FjX-=unwSO6u0pi1-Usm1yVW5hs5FHi=8Timg@mail.gmail.com>

During abbreviation checks, we navigate to the position within a pack-index that an OID would be inserted and check surrounding OIDs for the maximum matching prefix. This position may be beyond the last position, because the given OID is lexicographically larger than every OID in the pack. Then nth_packed_object_oid() does not initialize "oid".

Use the return value of nth_packed_object_oid() to prevent these errors.

Reported-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 sha1_name.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/sha1_name.c b/sha1_name.c
index 611c7d2..44dd595 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -546,17 +546,12 @@ static void find_abbrev_len_for_pack(struct packed_git *p,
 	 * nearby for the abbreviation length.
 	 */
 	mad->init_len = 0;
-	if (!match) {
-		nth_packed_object_oid(&oid, p, first);
+	if (!match && 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);
+	else if (first < num - 1 && nth_packed_object_oid(&oid, p, first + 1))
 		extend_abbrev_len(&oid, mad);
-	}
-	if (first > 0) {
-		nth_packed_object_oid(&oid, p, first - 1);
+	if (first > 0 && nth_packed_object_oid(&oid, p, first - 1))
 		extend_abbrev_len(&oid, mad);
-	}
 	mad->init_len = mad->cur_len;
 }
 
-- 
2.7.4
Previous: Christian CouderNext: Jeff King
Message 6 of 14 in “Use of uninitialised value of size 8 in sha1_name.c”
  1. Christian CouderFeb 26, 2018
  2. Jeff KingFeb 26, 2018
  3. Christian CouderFeb 26, 2018
  4. Derrick StoleeFeb 26, 2018
  5. Christian CouderFeb 26, 2018
  6. sha1_name: fix uninitialized memory errorsDerrick Stolee, Feb 26, 2018
  7. Jeff KingFeb 26, 2018
  8. sha1_name: fix uninitialized memory errorsDerrick Stolee, Feb 27, 2018
  9. Jeff KingFeb 27, 2018
  10. Junio C HamanoFeb 27, 2018
  11. Jeff KingFeb 27, 2018
  12. Junio C HamanoFeb 28, 2018
  13. Derrick StoleeFeb 28, 2018
  14. Junio C HamanoFeb 28, 2018

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