4.10 and -stable fix for virtio_blk and virtually mapped stacks

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* 4.10 and -stable fix for virtio_blk and virtually mapped stacks
@ 2017-01-04  5:25 Christoph Hellwig
  2017-01-04  5:25 ` [PATCH] virtio_blk: avoid DMA to stack for the sense buffer Christoph Hellwig
  0 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2017-01-04  5:25 UTC (permalink / raw)
  To: axboe, mst, jasowang; +Cc: linux-block, virtualization, linux-kernel

Without this fix attempts to do scsi passthrough on virtio_blk will crash
the system on virtually mapped stacks, which is something happening during
boot with many distros.

^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04  5:25 4.10 and -stable fix for virtio_blk and virtually mapped stacks Christoph Hellwig
@ 2017-01-04  5:25 ` Christoph Hellwig
  2017-01-04  7:44   ` Jason Wang
                     ` (2 more replies)
  0 siblings, 3 replies; 10+ messages in thread
From: Christoph Hellwig @ 2017-01-04  5:25 UTC (permalink / raw)
  To: axboe, mst, jasowang; +Cc: linux-block, virtualization, linux-kernel

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 <hch@lst.de>
---
 drivers/block/virtio_blk.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 5545a67..3c3b8f6 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;
-- 
2.1.4

^ permalink raw reply related	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04  5:25 ` [PATCH] virtio_blk: avoid DMA to stack for the sense buffer Christoph Hellwig
@ 2017-01-04  7:44   ` Jason Wang
  2017-01-09 13:35     ` Christoph Hellwig
  2017-01-04 15:47   ` 王金浦
  2017-01-09 16:33   ` Michael S. Tsirkin
  2 siblings, 1 reply; 10+ messages in thread
From: Jason Wang @ 2017-01-04  7:44 UTC (permalink / raw)
  To: Christoph Hellwig, axboe, mst; +Cc: linux-block, virtualization, linux-kernel



On 2017年01月04日 13:25, Christoph Hellwig wrote:
> 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 <hch@lst.de>
> ---
>   drivers/block/virtio_blk.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 5545a67..3c3b8f6 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;

Acked-by: Jason Wang <jasowang@redhat.com>

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04  7:44   ` Jason Wang
@ 2017-01-09 13:35     ` Christoph Hellwig
  2017-01-09 15:56       ` Jens Axboe
  0 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2017-01-09 13:35 UTC (permalink / raw)
  To: Jason Wang
  Cc: Christoph Hellwig, axboe, mst, linux-block, virtualization,
	linux-kernel

Is someone going to pick the patch up and send it to Linus?  I keep
running into all kinds of boot failures whenever I forget to cherry
pick it into my development trees..

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-09 13:35     ` Christoph Hellwig
@ 2017-01-09 15:56       ` Jens Axboe
  0 siblings, 0 replies; 10+ messages in thread
From: Jens Axboe @ 2017-01-09 15:56 UTC (permalink / raw)
  To: Christoph Hellwig, Jason Wang
  Cc: mst, linux-block, virtualization, linux-kernel

On 01/09/2017 06:35 AM, Christoph Hellwig wrote:
> Is someone going to pick the patch up and send it to Linus?  I keep
> running into all kinds of boot failures whenever I forget to cherry
> pick it into my development trees..

I'll add it.

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04  5:25 ` [PATCH] virtio_blk: avoid DMA to stack for the sense buffer Christoph Hellwig
  2017-01-04  7:44   ` Jason Wang
@ 2017-01-04 15:47   ` 王金浦
  2017-01-05  9:57     ` Christoph Hellwig
  2017-01-09 16:33   ` Michael S. Tsirkin
  2 siblings, 1 reply; 10+ messages in thread
From: 王金浦 @ 2017-01-04 15:47 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Jens Axboe, mst, jasowang, linux-block, virtualization, LKML

Hi Christoph,

2017-01-04 6:25 GMT+01:00 Christoph Hellwig <hch@lst.de>:
> 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.

This sounds scary.
Could you share how to reproduce it, this should go into stable if
it's the case.

Thanks,
Jinpu

>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/block/virtio_blk.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 5545a67..3c3b8f6 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;
> --
> 2.1.4
>

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04 15:47   ` 王金浦
@ 2017-01-05  9:57     ` Christoph Hellwig
  2017-01-05 10:37       ` 王金浦
  0 siblings, 1 reply; 10+ messages in thread
From: Christoph Hellwig @ 2017-01-05  9:57 UTC (permalink / raw)
  To: 王金浦
  Cc: Christoph Hellwig, Jens Axboe, mst, jasowang, linux-block,
	virtualization, LKML

On Wed, Jan 04, 2017 at 04:47:03PM +0100, 王金浦 wrote:
> This sounds scary.
> Could you share how to reproduce it, this should go into stable if
> it's the case.

Step 1: Build your kernel with CONFIG_VMAP_STACK=y
Step 2: issue a SG_IO ioctl, e.g. sg_inq /dev/vda

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-05  9:57     ` Christoph Hellwig
@ 2017-01-05 10:37       ` 王金浦
  2017-01-05 11:17         ` Christoph Hellwig
  0 siblings, 1 reply; 10+ messages in thread
From: 王金浦 @ 2017-01-05 10:37 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Jens Axboe, mst, jasowang, linux-block, virtualization, LKML

2017-01-05 10:57 GMT+01:00 Christoph Hellwig <hch@lst.de>:
> On Wed, Jan 04, 2017 at 04:47:03PM +0100, =E7=8E=8B=E9=87=91=E6=B5=A6 wro=
te:
>> This sounds scary.
>> Could you share how to reproduce it, this should go into stable if
>> it's the case.
>
> Step 1: Build your kernel with CONFIG_VMAP_STACK=3Dy
> Step 2: issue a SG_IO ioctl, e.g. sg_inq /dev/vda
>
Thanks, so it's only relevant to kernel > 4.9, as  CONFIG_VMAP_STACK
only introduced in 4.9 kernel.

Regards,
Jinpu

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-05 10:37       ` 王金浦
@ 2017-01-05 11:17         ` Christoph Hellwig
  0 siblings, 0 replies; 10+ messages in thread
From: Christoph Hellwig @ 2017-01-05 11:17 UTC (permalink / raw)
  To: 王金浦
  Cc: Christoph Hellwig, Jens Axboe, mst, jasowang, linux-block,
	virtualization, LKML

On Thu, Jan 05, 2017 at 11:37:46AM +0100, 王金浦 wrote:
> Thanks, so it's only relevant to kernel > 4.9, as  CONFIG_VMAP_STACK
> only introduced in 4.9 kernel.

kernel >= 4.9, but otherwise, yes.

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH] virtio_blk: avoid DMA to stack for the sense buffer
  2017-01-04  5:25 ` [PATCH] virtio_blk: avoid DMA to stack for the sense buffer Christoph Hellwig
  2017-01-04  7:44   ` Jason Wang
  2017-01-04 15:47   ` 王金浦
@ 2017-01-09 16:33   ` Michael S. Tsirkin
  2 siblings, 0 replies; 10+ messages in thread
From: Michael S. Tsirkin @ 2017-01-09 16:33 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: axboe, jasowang, linux-block, virtualization, linux-kernel

On Wed, Jan 04, 2017 at 08:25:05AM +0300, Christoph Hellwig wrote:
> 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 <hch@lst.de>
> ---
>  drivers/block/virtio_blk.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 5545a67..3c3b8f6 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);

I would prefer sizeof(vbr->sense) here to avoid duplication.
Otherwise:

Acked-by: Michael S. Tsirkin <mst@redhat.com>


>  		sgs[num_out + num_in++] = &sense;
>  		sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
>  		sgs[num_out + num_in++] = &inhdr;
> -- 
> 2.1.4

^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2017-01-09 16:33 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-01-04  5:25 4.10 and -stable fix for virtio_blk and virtually mapped stacks Christoph Hellwig
2017-01-04  5:25 ` [PATCH] virtio_blk: avoid DMA to stack for the sense buffer Christoph Hellwig
2017-01-04  7:44   ` Jason Wang
2017-01-09 13:35     ` Christoph Hellwig
2017-01-09 15:56       ` Jens Axboe
2017-01-04 15:47   ` 王金浦
2017-01-05  9:57     ` Christoph Hellwig
2017-01-05 10:37       ` 王金浦
2017-01-05 11:17         ` Christoph Hellwig
2017-01-09 16:33   ` Michael S. Tsirkin

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