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>

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 0b7645b13df14211dcf38fd9e433e1097b5b4298..4a19686fcfe9a922ead806d98b62f07144f0c832 100644 (file)
--- 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 */