From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35793) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WCQ2V-0003Rr-LC for qemu-devel@nongnu.org; Sun, 09 Feb 2014 03:47:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WCQ2R-000193-DB for qemu-devel@nongnu.org; Sun, 09 Feb 2014 03:46:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:7778) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WCQ2R-00018w-4z for qemu-devel@nongnu.org; Sun, 09 Feb 2014 03:46:55 -0500 From: Kevin Wolf Date: Sun, 9 Feb 2014 09:46:22 +0100 Message-Id: <1391935590-12264-11-git-send-email-kwolf@redhat.com> In-Reply-To: <1391935590-12264-1-git-send-email-kwolf@redhat.com> References: <1391935590-12264-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 10/18] qcow2: fix offset overflow in qcow2_alloc_clusters_at() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: anthony@codemonkey.ws Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Hu Tao When cluster size is big enough it can lead to an offset overflow in qcow2_alloc_clusters_at(). This patch fixes it. The allocation is stopped each time at L2 table boundary (see handle_alloc()), so the possible maximum bytes could be 2^(cluster_bits - 3 + cluster_bits) cluster_bits - 3 is used to compute the number of entry by L2 and the additional cluster_bits is to take into account each clusters referenced by the L2 entries. so int is safe for cluster_bits<=17, unsafe otherwise. Signed-off-by: Hu Tao Reviewed-by: Max Reitz Reviewed-by: Benoit Canet Signed-off-by: Kevin Wolf --- block/qcow2-refcount.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index c974abe..8712d8b 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -676,7 +676,13 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, BDRVQcowState *s = bs->opaque; uint64_t cluster_index; uint64_t old_free_cluster_index; - int i, refcount, ret; + uint64_t i; + int refcount, ret; + + assert(nb_clusters >= 0); + if (nb_clusters == 0) { + return 0; + } /* Check how many clusters there are free */ cluster_index = offset >> s->cluster_bits; -- 1.8.1.4