From: Peter Lieven Date: Tue, 12 Nov 2013 12:48:07 +0000 (+0100) Subject: qcow2: fix possible corruption when reading multiple clusters X-Git-Tag: v1.6.2~15 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4d2f39a918ab4ccac7255da143b4322a9b4b204a;p=thirdparty%2Fqemu.git qcow2: fix possible corruption when reading multiple clusters if multiple sectors spanning multiple clusters are read the function count_contiguous_clusters should ensure that the cluster type should not change between the clusters. Especially the for-loop should break when we have one or more normal clusters followed by a compressed cluster. Unfortunately the wrong macro was used in the mask to compare the flags. This was discovered while debugging a data corruption issue when converting a compressed qcow2 image to raw. qemu-img reads 2MB chunks which span multiple clusters. CC: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Signed-off-by: Kevin Wolf (cherry picked from commit 78a52ad5acca7053b774fcc80290e7b7e224c80a) Signed-off-by: Michael Roth --- diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index fd3054b2d8b..b558eb0be3c 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -266,7 +266,7 @@ static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, uint64_t *l2_table, uint64_t start, uint64_t stop_flags) { int i; - uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW2_CLUSTER_COMPRESSED; + uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED; uint64_t first_entry = be64_to_cpu(l2_table[0]); uint64_t offset = first_entry & mask;