scsi: virtio_scsi: Add validation for residual bytes from response

YongjiXie · martinkpetersen · commit 5f638e5ac61e · 2021-06-29T16:54:08.000-04:00
This ensures that the residual bytes in response (might come from an untrusted device) will not exceed the data buffer length. Link: https://lore.kernel.org/r/20210615105218.214-1-xieyongji@bytedance.com Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Xie Yongji <xieyongji@bytedance.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
@@ -97,7 +97,7 @@ static inline struct Scsi_Host *virtio_scsi_host(struct virtio_device *vdev)
 static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid)
 {
 	if (resid)
-		scsi_set_resid(sc, resid);
+		scsi_set_resid(sc, min(resid, scsi_bufflen(sc)));
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -97,7 +97,7 @@ static inline struct Scsi_Host virtio_scsi_host(struct virtio_device vdev)`
`97`	`97`	`static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid)`
`98`	`98`	`{`
`99`	`99`	`if (resid)`
`100`		`- scsi_set_resid(sc, resid);`
	`100`	`+ scsi_set_resid(sc, min(resid, scsi_bufflen(sc)));`
`101`	`101`	`}`
`102`	`102`
`103`	`103`	`/*`