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

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
hifive-unleashed-5.1
Ewan D. Milne 2012-11-02 09:38:34 -04:00 committed by James Bottomley
parent c3ccb1d7cf
commit 085b513f97
1 changed files with 7 additions and 15 deletions
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22
drivers/scsi/sd.c
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@ -838,10 +838,17 @@ 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;
}
}
/**
@ -1720,21 +1727,6 @@ 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;
}