From 39c58f37a10198054c656c28202fb1e6d22fd505 Mon Sep 17 00:00:00 2001
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Date: Thu, 18 Jun 2009 17:04:00 +0200
Subject: [PATCH] ide-cd: prevent null pointer deref via cdrom_newpc_intr

With 2.6.30, the error handling code in cdrom_newpc_intr was changed
to deal with partial request failures by normally completing the 'good'
parts of a request and only 'error' the last (and presumably,
incompletely transferred) bio associated with a particular
request. In order to do this, ide_complete_rq is called over
ide_cd_error_cmd() to partially complete the rq. The block layer
does partial completion only for requests with bio's and if the
rq doesn't have one (eg 'GPCMD_READ_DISC_INFO') the request is
completed as a whole and the drive->hwif->rq pointer set to NULL
afterwards. When calling ide_complete_rq again to report
the error, this null pointer is derefenced, resulting in a kernel
crash.

This fixes http://bugzilla.kernel.org/show_bug.cgi?id=13399.

Signed-off-by: Rainer Weikusat <rweikusat@mssgmbh.com>
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 drivers/ide/ide-cd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 0b7645b13df1..4a19686fcfe9 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -667,7 +667,7 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 				rq->errors = -EIO;
 		}
 
-		if (uptodate == 0)
+		if (uptodate == 0 && rq->bio)
 			ide_cd_error_cmd(drive, cmd);
 
 		/* make sure it's fully ended */
-- 
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