Commit 2a5f07b5 authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik

libata: fix NULL sdev dereference race in atapi_qc_complete()

SCSI commands may be issued between __scsi_add_device() and dev->sdev
assignment, so it's unsafe for ata_qc_complete() to dereference
dev->sdev->locked without checking whether it's NULL or not.  Fix it.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent a0a6da1a
...@@ -2552,8 +2552,11 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc) ...@@ -2552,8 +2552,11 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
* *
* If door lock fails, always clear sdev->locked to * If door lock fails, always clear sdev->locked to
* avoid this infinite loop. * avoid this infinite loop.
*
* This may happen before SCSI scan is complete. Make
* sure qc->dev->sdev isn't NULL before dereferencing.
*/ */
if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL) if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL && qc->dev->sdev)
qc->dev->sdev->locked = 0; qc->dev->sdev->locked = 0;
qc->scsicmd->result = SAM_STAT_CHECK_CONDITION; qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;
......
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