From: Christoph Hellwig Date: Mon, 9 Jan 2017 15:56:23 +0000 (-0700) Subject: virtio_blk: avoid DMA to stack for the sense buffer X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a14d749fcebe97ddf6af6db3d1f6ece85c9ddcb9;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git virtio_blk: avoid DMA to stack for the sense buffer Most users of BLOCK_PC requests allocate the sense buffer on the stack, so to avoid DMA to the stack copy them to a field in the heap allocated virtblk_req structure. Without that any attempt at SCSI passthrough I/O, including the SG_IO ioctl from userspace will crash the kernel. Note that this includes running tools like hdparm even when the host does not have SCSI passthrough enabled. Signed-off-by: Christoph Hellwig Cc: stable@vger.kernel.org # v4.9+ Signed-off-by: Jens Axboe --- diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 5545a679abd8..3c3b8f601469 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -56,6 +56,7 @@ struct virtblk_req { struct virtio_blk_outhdr out_hdr; struct virtio_scsi_inhdr in_hdr; u8 status; + u8 sense[SCSI_SENSE_BUFFERSIZE]; struct scatterlist sg[]; }; @@ -102,7 +103,8 @@ static int __virtblk_add_req(struct virtqueue *vq, } if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) { - sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE); + memcpy(vbr->sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE); + sg_init_one(&sense, vbr->sense, SCSI_SENSE_BUFFERSIZE); sgs[num_out + num_in++] = &sense; sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr)); sgs[num_out + num_in++] = &inhdr;