From: Kevin Wolf Date: Tue, 16 Feb 2010 14:54:49 +0000 (+0100) Subject: qcow2: Fix access after end of array X-Git-Tag: v0.13.0-rc0~1321 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4805bb66969622f86376191c94c4748bce91e6be;p=thirdparty%2Fqemu.git qcow2: Fix access after end of array If a write requests crosses a L2 table boundary and all clusters until the end of the L2 table are usable for the request, we must not look at the next L2 entry because we already have arrived at the end of the array. Signed-off-by: Kevin Wolf Signed-off-by: Anthony Liguori --- diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 3501a94296d..b13b6935f80 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -750,12 +750,15 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, while (i < nb_clusters) { i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, &l2_table[l2_index], i, 0); - - if(be64_to_cpu(l2_table[l2_index + i])) + if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { break; + } i += count_contiguous_free_clusters(nb_clusters - i, &l2_table[l2_index + i]); + if (i >= nb_clusters) { + break; + } cluster_offset = be64_to_cpu(l2_table[l2_index + i]); @@ -763,6 +766,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, (cluster_offset & QCOW_OFLAG_COMPRESSED)) break; } + assert(i <= nb_clusters); nb_clusters = i; /*