On 10-11-01 06:39 AM, Tejun Heo wrote:
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@xxxxxxxxxx> Cc: stable@xxxxxxxxxx --- I actually hit this race condition. Lucky me. :-) Thanks. drivers/ata/libata-scsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) Index: work/drivers/ata/libata-scsi.c =================================================================== --- work.orig/drivers/ata/libata-scsi.c +++ work/drivers/ata/libata-scsi.c @@ -2552,8 +2552,11 @@ 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;
Mmmm.. for some reason, this just screams "band-aid" to me, and makes me worry deeply about the underlaying race condition it all suggests.. James? -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
