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authorTejun Heo <tj@kernel.org>2010-11-01 11:39:19 +0100
committerJeff Garzik <jgarzik@redhat.com>2010-11-12 17:10:51 -0500
commit2a5f07b5ec098edc69e05fdd2f35d3fbb1235723 (patch)
tree28180df99e2b236018c29dd05480b13024159868 /drivers
parenta0a6da1a735ba66c04019b39cca8f79008d6c434 (diff)
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: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/ata/libata-scsi.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index d050e073e57..3f91c01c217 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2552,8 +2552,11 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
*
* If door lock fails, always clear sdev->locked to
* 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->scsicmd->result = SAM_STAT_CHECK_CONDITION;