From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36467) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VTpMH-0006vG-Jn for qemu-devel@nongnu.org; Wed, 09 Oct 2013 04:43:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VTpMB-0007XB-L2 for qemu-devel@nongnu.org; Wed, 09 Oct 2013 04:43:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46248) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VTpMB-0007X3-C5 for qemu-devel@nongnu.org; Wed, 09 Oct 2013 04:42:59 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r998gwFR008293 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 9 Oct 2013 04:42:58 -0400 From: Max Reitz Date: Wed, 9 Oct 2013 10:42:56 +0200 Message-Id: <1381308176-22635-1-git-send-email-mreitz@redhat.com> Subject: [Qemu-devel] [PATCH] qcow2: Use pread for inactive L1 in overlap check List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi , Max Reitz Currently, qcow2_check_metadata_overlap uses bdrv_read to read inactive L1 tables from disk. The number of sectors to read is calculated through a truncating integer division, therefore, if the L1 table size is not a multiple of the sector size, the final entries will not be read and their entries in memory remain undefined (from the g_malloc). Using bdrv_pread fixes this. Signed-off-by: Max Reitz --- block/qcow2-refcount.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 2d67885..4cb9c23 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -1719,12 +1719,11 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int chk, int64_t offset, for (i = 0; i < s->nb_snapshots; i++) { uint64_t l1_ofs = s->snapshots[i].l1_table_offset; uint32_t l1_sz = s->snapshots[i].l1_size; - uint64_t *l1 = g_malloc(l1_sz * sizeof(uint64_t)); + uint64_t l1_sz2 = l1_sz * sizeof(uint64_t); + uint64_t *l1 = g_malloc(l1_sz2); int ret; - ret = bdrv_read(bs->file, l1_ofs / BDRV_SECTOR_SIZE, (uint8_t *)l1, - l1_sz * sizeof(uint64_t) / BDRV_SECTOR_SIZE); - + ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2); if (ret < 0) { g_free(l1); return ret; -- 1.8.3.1