SCSI: scsi_lib: fix potential NULL dereference

commit 03b147083a2f9a2a3fbbd2505fa88ffa3c6ab194 upstream.

Stanse found a potential NULL dereference in scsi_kill_request.

Instead of triggering BUG() in 'if (unlikely(cmd == NULL))' branch,
the kernel will Oops earlier on cmd dereference.

Move the dereferences after the if.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1ae7b7c848b9efe25b02d4aed13838725324214a..00e3961da07e44afc723f60d9b57b358bb5a4502 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1370,9 +1370,9 @@ static int scsi_lld_busy(struct request_queue *q)
 static void scsi_kill_request(struct request *req, struct request_queue *q)
 {
        struct scsi_cmnd *cmd = req->special;
-       struct scsi_device *sdev = cmd->device;
-       struct scsi_target *starget = scsi_target(sdev);
-       struct Scsi_Host *shost = sdev->host;
+       struct scsi_device *sdev;
+       struct scsi_target *starget;
+       struct Scsi_Host *shost;
 
        blk_start_request(req);
 
@@ -1382,6 +1382,9 @@ static void scsi_kill_request(struct request *req, struct request_queue *q)
                BUG();
        }
 
+       sdev = cmd->device;
+       starget = scsi_target(sdev);
+       shost = sdev->host;
        scsi_init_cmd_errh(cmd);
        cmd->result = DID_NO_CONNECT << 16;
        atomic_inc(&cmd->device->iorequest_cnt);