From 7cb6d3c9be2cbda05d2b14e7897e74839e48fbb2 Mon Sep 17 00:00:00 2001 From: Liam Merwick Date: Mon, 5 Nov 2018 21:38:39 +0000 Subject: [PATCH] qcow2: Read outside array bounds in qcow2_pre_write_overlap_check() The commit for 0e4e4318eaa5 increments QCOW2_OL_MAX_BITNR but does not add an array entry for QCOW2_OL_BITMAP_DIRECTORY_BITNR to metadata_ol_names[]. As a result, an array dereference of metadata_ol_names[8] in qcow2_pre_write_overlap_check() could result in a read outside of the array bounds. Fixes: 0e4e4318eaa5 ('qcow2: add overlap check for bitmap directory') Cc: Vladimir Sementsov-Ogievskiy Signed-off-by: Liam Merwick Reviewed-by: Eric Blake Reviewed-by: Max Reitz Message-id: 1541453919-25973-6-git-send-email-Liam.Merwick@oracle.com Signed-off-by: Max Reitz --- block/qcow2-refcount.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 3c539f02e5..46082aeac1 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -2719,15 +2719,17 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset, } static const char *metadata_ol_names[] = { - [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header", - [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table", - [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table", - [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table", - [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block", - [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table", - [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table", - [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table", + [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header", + [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table", + [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table", + [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table", + [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block", + [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table", + [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table", + [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table", + [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = "bitmap directory", }; +QEMU_BUILD_BUG_ON(QCOW2_OL_MAX_BITNR != ARRAY_SIZE(metadata_ol_names)); /* * First performs a check for metadata overlaps (through