block,scsi: verify return pointer from blk_get_request

The blk-core dead queue checks introduce an error scenario to
blk_get_request that returns NULL if the request queue has been
shutdown. This affects the behavior for __GFP_WAIT callers, who should
verify the return value before dereferencing.

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

4 files changed, 14 insertions, 1 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 51bf5155ee75..29d056782833 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -448,6 +448,10 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
         }
 
         rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
+        if (!rq) {
+                err = -ENODEV;
+                goto error_free_buffer;
+        }
 
         cmdlen = COMMAND_SIZE(opcode);
 
@@ -520,8 +524,9 @@ out:
         }
         
 error:
-        kfree(buffer);
         blk_put_request(rq);
+error_free_buffer:
+        kfree(buffer);
         return err;
 }
 EXPORT_SYMBOL_GPL(sg_scsi_ioctl);
@@ -534,6 +539,8 @@ static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk,
         int err;
 
         rq = blk_get_request(q, WRITE, __GFP_WAIT);
+        if (!rq)
+                return -ENODEV;
         blk_rq_set_block_pc(rq);
         rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
         rq->cmd[0] = cmd;
diff --git a/drivers/block/paride/pd.c b/drivers/block/paride/pd.c
index fea7e76a00de..ca831f741d89 100644
--- a/drivers/block/paride/pd.c
+++ b/drivers/block/paride/pd.c
@@ -722,6 +722,8 @@ static int pd_special_command(struct pd_unit *disk,
         int err = 0;
 
         rq = blk_get_request(disk->gd->queue, READ, __GFP_WAIT);
+        if (!rq)
+                return -ENODEV;
 
         rq->cmd_type = REQ_TYPE_SPECIAL;
         rq->special = func;
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 758ac442c5b5..7fa8c80e8982 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -704,6 +704,8 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
 
         rq = blk_get_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
                              WRITE : READ, __GFP_WAIT);
+        if (!rq)
+                return -ENODEV;
         blk_rq_set_block_pc(rq);
 
         if (cgc->buflen) {
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 5db8454474ee..4c433bf47a06 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1960,6 +1960,8 @@ static void scsi_eh_lock_door(struct scsi_device *sdev)
          * request becomes available
          */
         req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
+        if (!req)
+                return;
 
         blk_rq_set_block_pc(req);