Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965815AbcCJLje (ORCPT ); Thu, 10 Mar 2016 06:39:34 -0500 Received: from mail-pf0-f171.google.com ([209.85.192.171]:34396 "EHLO mail-pf0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752164AbcCJLjY (ORCPT ); Thu, 10 Mar 2016 06:39:24 -0500 From: Sudip Mukherjee To: Jens Axboe , Jens Axboe Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Sudip Mukherjee Subject: [PATCH] block: fix possible NULL dereference Date: Thu, 10 Mar 2016 17:09:13 +0530 Message-Id: <1457609953-24101-1-git-send-email-sudipm.mukherjee@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 986 Lines: 31 We were checking for iter to be NULL after dereferencing it. Lets first check it and then use it. Signed-off-by: Sudip Mukherjee --- block/blk-map.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/blk-map.c b/block/blk-map.c index a54f054..089ed59 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -126,7 +126,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, const struct iov_iter *iter, gfp_t gfp_mask) { struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0}; - bool copy = (q->dma_pad_mask & iter->count) || map_data; + bool copy; struct bio *bio = NULL; struct iov_iter i; int ret; @@ -134,6 +134,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, if (!iter || !iter->count) return -EINVAL; + copy = (q->dma_pad_mask & iter->count) || map_data; iov_for_each(iov, i, *iter) { unsigned long uaddr = (unsigned long) iov.iov_base; -- 1.9.1