[patch] possible fix

idecd.patch (text/plain), 1.59 KB, created by Daniel Drake (RETIRED) on 2009-06-21 15:16:29 UTC

From: Rainer Weikusat <[e-mail]>
Date: Thu, 18 Jun 2009 15:04:00 +0000 (+0200)
Subject: ide-cd: prevent null pointer deref via cdrom_newpc_intr
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fbart%2Fide-2.6.git;a=commitdiff_plain;h=39c58f37a10198054c656c28202fb1e6d22fd505

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 <[e-mail]>
Signed-off-by: Borislav Petkov <[e-mail]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[e-mail]>
---

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 0b7645b..4a19686 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -667,7 +667,7 @@ out_end:
 				rq->errors = -EIO;
 		}
 
-		if (uptodate == 0)
+		if (uptodate == 0 && rq->bio)
 			ide_cd_error_cmd(drive, cmd);
 
 		/* make sure it's fully ended */