From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43072) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YsOxg-0001mf-SV for qemu-devel@nongnu.org; Wed, 13 May 2015 01:12:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YsOxd-0004C7-Ny for qemu-devel@nongnu.org; Wed, 13 May 2015 01:12:04 -0400 From: Fam Zheng Date: Wed, 13 May 2015 13:11:58 +0000 Message-Id: <1431522721-3266-1-git-send-email-famz@redhat.com> Subject: [Qemu-devel] [PATCH v7 0/3] block: Fix unaligned bdrv_aio_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , pbonzini@redhat.com, qemu-block@nongnu.org, Stefan Hajnoczi , qemu-stable@nongnu.org v7: Add Kevin's rev-by in patch 1 and 3. Address Stefan's and Kevin's comments on patch 2: - Don't duplicate tracked_request_begin and tracked_request_end; - Don't forget to remove debug printf; - Call qemu_vfree unconditionally; - Don't serialize aligned part of the zero write req; An unaligned zero write causes NULL deferencing in bdrv_co_do_pwritev. That path is reachable from bdrv_co_write_zeroes and bdrv_aio_write_zeroes. You can easily trigger through the former with qemu-io, as the test case added by 61815d6e0aa. For bdrv_aio_write_zeroes, in common cases there's always a format driver (which uses 512 alignment), so it would be much rarer to have unaligned requests (only concerning top level here, when the request goes down to bs->file, where for example the alignment is 4k, it would then be calling bdrv_co_write_zeroes because it's in a coroutine). fc3959e4669a1c fixed bdrv_co_write_zeroes but not bdrv_aio_write_zeroes. The lattern is the actually used one by device model. Revert the previous fix, do it in bdrv_co_do_pwritev, to cover both paths. Fam Zheng (3): Revert "block: Fix unaligned zero write" block: Fix NULL deference for unaligned write if qiov is NULL qemu-iotests: Test unaligned sub-block zero write block/io.c | 142 ++++++++++++++++++++++++++++++++------------- tests/qemu-iotests/033 | 13 +++++ tests/qemu-iotests/033.out | 30 ++++++++++ 3 files changed, 144 insertions(+), 41 deletions(-) -- 2.4.0