sym53c8xx: Fix NULL pointer dereference in slave_destroy

commit cced5041ed5a2d1352186510944b0ddfbdbe4c0b upstream.

sym53c8xx_slave_destroy unconditionally assumes that sym53c8xx_slave_alloc has
succesesfully allocated a sym_lcb. This can lead to a NULL pointer dereference
(exposed by commit 4e6c82b).

Signed-off-by: Stratos Psomadakis <psomas@gentoo.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index b4543f575f4..36d1ed7817e 100644
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -839,6 +839,10 @@ static void sym53c8xx_slave_destroy(struct scsi_device *sdev)
         struct sym_lcb *lp = sym_lp(tp, sdev->lun);
         unsigned long flags;
 
+        /* if slave_alloc returned before allocating a sym_lcb, return */
+        if (!lp)
+                return;
+
         spin_lock_irqsave(np->s.host->host_lock, flags);
 
         if (lp->busy_itlq || lp->busy_itl) {