ide-cd: prevent null pointer deref via cdrom_newpc_intr
authorRainer Weikusat <rweikusat@mssgmbh.com>
Thu, 18 Jun 2009 15:04:00 +0000 (17:04 +0200)
committerBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Sat, 20 Jun 2009 10:22:47 +0000 (12:22 +0200)
commit39c58f37a10198054c656c28202fb1e6d22fd505
treef0a321782a02f8fde4a68ffd8627771ff6be1e02
parent2c7eaa43c3bb7b3b9fe2051d17f308c1f0728c78
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