From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757173Ab2HOULH (ORCPT ); Wed, 15 Aug 2012 16:11:07 -0400 Received: from mail.windriver.com ([147.11.1.11]:37033 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756940Ab2HOTv6 (ORCPT ); Wed, 15 Aug 2012 15:51:58 -0400 From: Paul Gortmaker To: , CC: Petr Uzel , James Bottomley , Paul Gortmaker Subject: [v2.6.34-stable 120/165] [SCSI] st: fix race in st_scsi_execute_end Date: Wed, 15 Aug 2012 15:47:44 -0400 Message-ID: <1345060109-9187-121-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.12.rc2 In-Reply-To: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Petr Uzel ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit c68bf8eeaa57c852e74adcf597237be149eef830 upstream. The call to complete() in st_scsi_execute_end() wakes up sleeping thread in write_behind_check(), which frees the st_request, thus invalidating the pointer to the associated bio structure, which is then passed to the blk_rq_unmap_user(). Fix by storing pointer to bio structure into temporary local variable. This bug is present since at least linux-2.6.32. Signed-off-by: Petr Uzel Reported-by: Juergen Groß Reviewed-by: Jan Kara Acked-by: Kai Mäkisara Signed-off-by: James Bottomley Signed-off-by: Paul Gortmaker --- drivers/scsi/st.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index 3ea1a71..516ca15 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -462,14 +462,16 @@ static void st_scsi_execute_end(struct request *req, int uptodate) { struct st_request *SRpnt = req->end_io_data; struct scsi_tape *STp = SRpnt->stp; + struct bio *tmp; STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors; STp->buffer->cmdstat.residual = req->resid_len; + tmp = SRpnt->bio; if (SRpnt->waiting) complete(SRpnt->waiting); - blk_rq_unmap_user(SRpnt->bio); + blk_rq_unmap_user(tmp); __blk_put_request(req->q, req); } -- 1.7.12.rc2