Commit 59a5e266 authored Jul 19, 2017 by Dan Carpenter Committed by Tejun Heo Jul 19, 2017

libata: array underflow in ata_find_dev()



My static checker complains that "devno" can be negative, meaning that
we read before the start of the loop.  I've looked at the code, and I
think the warning is right.  This come from /proc so it's root only or
it would be quite a quite a serious bug.  The call tree looks like this:

proc_scsi_write() <- gets id and channel from simple_strtoul()
-> scsi_add_single_device() <- calls shost->transportt->user_scan()
   -> ata_scsi_user_scan()
      -> ata_find_dev()

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # all versions at this point

parent 6ac1d153

drivers/ata/libata-scsi.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -3030,10 +3030,12 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
		static struct ata_device ata_find_dev(struct ata_port ap, int devno)
		{
		if (!sata_pmp_attached(ap)) {
		if (likely(devno < ata_link_max_devices(&ap->link)))
		if (likely(devno >= 0 &&
		devno < ata_link_max_devices(&ap->link)))
		return &ap->link.device[devno];
		} else {
		if (likely(devno < ap->nr_pmp_links))
		if (likely(devno >= 0 &&
		devno < ap->nr_pmp_links))
		return &ap->pmp_link[devno].device[0];
		}