From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41176) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X4Z6L-0004St-G0 for qemu-devel@nongnu.org; Tue, 08 Jul 2014 13:23:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X4Z5m-0000Nv-An for qemu-devel@nongnu.org; Tue, 08 Jul 2014 13:22:45 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:35136) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X4Z5l-0000NU-TD for qemu-devel@nongnu.org; Tue, 08 Jul 2014 13:22:10 -0400 Received: from /spool/local by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 8 Jul 2014 11:22:09 -0600 From: Michael Roth Date: Tue, 8 Jul 2014 12:18:05 -0500 Message-Id: <1404839947-1086-95-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1404839947-1086-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1404839947-1086-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 094/156] qcow2: fix offset overflow in qcow2_alloc_clusters_at() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@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 (cherry picked from commit 33304ec9fa484e765c6249673e09e1b7d49c5b85) Signed-off-by: Michael Roth --- 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 8c57016..6c212c9 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -678,7 +678,13 @@ 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; -- 1.9.1