From ab08ee14393724ab52b92be643d588d41a1a05be Mon Sep 17 00:00:00 2001 From: Maurizio Lombardi Date: Wed, 18 Nov 2015 15:32:44 +0100 Subject: [PATCH] st: fix potential null pointer dereference. If cdev_add() returns an error, the code calls cdev_del() passing the STm->cdevs[rew] pointer as parameter; the problem is that the pointer has not been initialized yet. This patch fixes the problem by moving the STm->cdevs[rew] pointer initialization before the call to cdev_add(). It also sets STm->devs[rew] and STm->cdevs[rew] to NULL in case of failure. Signed-off-by: Maurizio Lombardi Reviewed-by: Johannes Thumshirn Reviewed-by: Tomas Henzl Signed-off-by: Martin K. Petersen --- drivers/scsi/st.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index b37b9b00c4b460..3e79c80bf6c6fb 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -4083,6 +4083,7 @@ static int create_one_cdev(struct scsi_tape *tape, int mode, int rew) } cdev->owner = THIS_MODULE; cdev->ops = &st_fops; + STm->cdevs[rew] = cdev; error = cdev_add(cdev, cdev_devno, 1); if (error) { @@ -4091,7 +4092,6 @@ static int create_one_cdev(struct scsi_tape *tape, int mode, int rew) pr_err("st%d: Device not attached.\n", dev_num); goto out_free; } - STm->cdevs[rew] = cdev; i = mode << (4 - ST_NBR_MODE_BITS); snprintf(name, 10, "%s%s%s", rew ? "n" : "", @@ -4110,8 +4110,9 @@ static int create_one_cdev(struct scsi_tape *tape, int mode, int rew) return 0; out_free: cdev_del(STm->cdevs[rew]); - STm->cdevs[rew] = NULL; out: + STm->cdevs[rew] = NULL; + STm->devs[rew] = NULL; return error; }