| From | Andi Kleen <> | Subject | [PATCH] [139/223] libata: fix NULL sdev dereference race in atapi_qc_complete() | Date | Mon, 13 Dec 2010 00:47:21 +0100 (CET) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Tejun Heo <tj@kernel.org>
commit 2a5f07b5ec098edc69e05fdd2f35d3fbb1235723 upstream.
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> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- drivers/ata/libata-scsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
Index: linux/drivers/ata/libata-scsi.c =================================================================== --- linux.orig/drivers/ata/libata-scsi.c +++ linux/drivers/ata/libata-scsi.c @@ -2577,8 +2577,11 @@ static void atapi_qc_complete(struct ata * * 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;
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