From df2adab2575fa19764b744edafea1a202f904912 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 5 Mar 2015 10:41:34 +0000 Subject: [PATCH] qcow2: Fix NULL dereference in qcow2_open() error path (CVE-2014-0146) The qcow2 code assumes that s->snapshots is non-NULL if s->nb_snapshots != 0. By having the initialisation of both fields separated in qcow2_open(), any error occuring in between would cause the error path to dereference NULL in qcow2_free_snapshots() if the image had any snapshots. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Signed-off-by: Stefan Hajnoczi Signed-off-by: Stefano Stabellini --- block/qcow2.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index d7805ce94..b7d204f48 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -203,9 +203,6 @@ static int qcow2_open(BlockDriverState *bs, int flags) s->refcount_table_size = header.refcount_table_clusters << (s->cluster_bits - 3); - s->snapshots_offset = header.snapshots_offset; - s->nb_snapshots = header.nb_snapshots; - /* read the level 1 table */ s->l1_size = header.l1_size; s->l1_vm_state_index = size_to_l1(s, header.size); @@ -273,6 +270,11 @@ static int qcow2_open(BlockDriverState *bs, int flags) } bs->backing_file[len] = '\0'; } + + /* Internal snapshots */ + s->snapshots_offset = header.snapshots_offset; + s->nb_snapshots = header.nb_snapshots; + if (qcow2_read_snapshots(bs) < 0) { ret = -EINVAL; goto fail; -- 2.39.5