SCSI: sd: fix crash when UA received on DIF enabled device

commit 085b513f97d8d799d28491239be4b451bcd8c2c5 upstream.

sd_prep_fn will allocate a larger CDB for the command via mempool_alloc
for devices using DIF type 2 protection.  This CDB was being freed
in sd_done, which results in a kernel crash if the command is retried
due to a UNIT ATTENTION.  This change moves the code to free the larger
CDB into sd_unprep_fn instead, which is invoked after the request is
complete.

It is no longer necessary to call scsi_print_command separately for
this case as the ->cmnd will no longer be NULL in the normal code path.

Also removed conditional test for DIF type 2 when freeing the larger
CDB because the protection_type could have been changed via sysfs while
the command was executing.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 15 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 1b1125e67f1e..610417ec45af 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -828,10 +828,17 @@ static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
 
 static void sd_unprep_fn(struct request_queue *q, struct request *rq)
 {
+        struct scsi_cmnd *SCpnt = rq->special;
+
         if (rq->cmd_flags & REQ_DISCARD) {
                 free_page((unsigned long)rq->buffer);
                 rq->buffer = NULL;
         }
+        if (SCpnt->cmnd != rq->cmd) {
+                mempool_free(SCpnt->cmnd, sd_cdb_pool);
+                SCpnt->cmnd = NULL;
+                SCpnt->cmd_len = 0;
+        }
 }
 
 /**
@@ -1710,21 +1717,6 @@ static int sd_done(struct scsi_cmnd *SCpnt)
         if (rq_data_dir(SCpnt->request) == READ && scsi_prot_sg_count(SCpnt))
                 sd_dif_complete(SCpnt, good_bytes);
 
-        if (scsi_host_dif_capable(sdkp->device->host, sdkp->protection_type)
-            == SD_DIF_TYPE2_PROTECTION && SCpnt->cmnd != SCpnt->request->cmd) {
-
-                /* We have to print a failed command here as the
-                 * extended CDB gets freed before scsi_io_completion()
-                 * is called.
-                 */
-                if (result)
-                        scsi_print_command(SCpnt);
-
-                mempool_free(SCpnt->cmnd, sd_cdb_pool);
-                SCpnt->cmnd = NULL;
-                SCpnt->cmd_len = 0;
-        }
-
         return good_bytes;
 }