From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752434AbbCKREO (ORCPT ); Wed, 11 Mar 2015 13:04:14 -0400 Received: from mga02.intel.com ([134.134.136.20]:8487 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274AbbCKREJ (ORCPT ); Wed, 11 Mar 2015 13:04:09 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,382,1422950400"; d="scan'208";a="539465088" From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , "Roger C. Pao (Enmotus)" , Boaz Harrosh , linux-nvdimm@ml01.01.org, Nick Piggin Subject: [PATCH] brd: Ensure that bio_vecs have size <= PAGE_SIZE Date: Wed, 11 Mar 2015 11:02:33 -0600 Message-Id: <1426093353-23709-1-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 1.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The functions copy_from_brd() and copy_to_brd() are written with an assumption that the bio_vec they are given has size <= PAGE_SIZE. This assumption is not enforced in any way, and if the bio_vec has size larger than PAGE_SIZE data will just be lost. Such a situation can occur with I/Os generated from in-kernel sources, or with coalesced bio_vecs. This bug was originally reported against the pmem driver, where it was found using the Enmotus tiering engine. Instead we should have brd explicitly tell the block layer that it can handle data segments of at most PAGE_SIZE. Signed-off-by: Ross Zwisler Reported-by: Hugh Daschbach Cc: Roger C. Pao (Enmotus) Cc: Boaz Harrosh Cc: linux-nvdimm@lists.01.org Cc: Nick Piggin --- drivers/block/brd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 898b4f256782..7e4873361b64 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -490,6 +490,7 @@ static struct brd_device *brd_alloc(int i) blk_queue_make_request(brd->brd_queue, brd_make_request); blk_queue_max_hw_sectors(brd->brd_queue, 1024); blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); + blk_queue_max_segment_size(brd->brd_queue, PAGE_SIZE); brd->brd_queue->limits.discard_granularity = PAGE_SIZE; brd->brd_queue->limits.max_discard_sectors = UINT_MAX; -- 1.9.3