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.

[ WT: starget is not set in 2.6.27 ]

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>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 9899f6e4c5e86df2729f7caa4b44b5df5ad3cef3..88ed1eea273c5f8d94b42d95bcd09c42067ed7df 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1389,8 +1389,8 @@ static inline int scsi_host_queue_ready(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_Host *shost = sdev->host;
+       struct scsi_device *sdev;
+       struct Scsi_Host *shost;
 
        blkdev_dequeue_request(req);
 
@@ -1402,6 +1402,8 @@ static void scsi_kill_request(struct request *req, struct request_queue *q)
 
        scmd_printk(KERN_INFO, cmd, "killing request\n");
 
+       sdev = cmd->device;
+       shost = sdev->host;
        scsi_init_cmd_errh(cmd);
        cmd->result = DID_NO_CONNECT << 16;
        atomic_inc(&cmd->device->iorequest_cnt);