linux-kernel - [v2.6.34-stable 120/165] [SCSI] st: fix race in st_scsi_execute

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 15 Aug 2012 15:47:44 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	<stable@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	Petr Uzel <petr.uzel@...e.cz>,
	James Bottomley <JBottomley@...allels.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [v2.6.34-stable 120/165] [SCSI] st: fix race in st_scsi_execute_end

From: Petr Uzel <petr.uzel@...e.cz>

                   -------------------
    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 <petr.uzel@...e.cz>
Reported-by: Juergen Groß <juergen.gross@...fujitsu.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Acked-by: Kai Mäkisara <kai.makisara@...umbus.fi>
Signed-off-by: James Bottomley <JBottomley@...allels.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/