[SCSI] sym53c8xx: Fix NULL pointer dereference in slave_destroy

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>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index b4543f575f466fc3c7fed5f3edad05be9595d0cd..36d1ed7817ebf9d52631c970023d31b31ff494e0 100644 (file)
--- 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) {