[PATCH v3 0/4] Add blk_validate_block_size() helper for drivers to validate block size

[PATCH v3 0/4] Add blk_validate_block_size() helper for drivers to validate block size

[Xie Yongji]

The block layer can't support the block size larger than
page size yet, so driver needs to validate the block size
before setting it. Now this validation is done in device drivers
with some duplicated codes. This series tries to add a block
layer helper for it and makes loop driver, nbd driver and
virtio-blk driver use it.

We tested both invalid block size and valid block size cases
for loop driver with the example in man page [1] and for
nbd and virtio-blk driver with qemu-nbd and storage-daemon (vduse)
in the qemu repo [2].

[1] https://man7.org/linux/man-pages/man4/loop.4.html
[2] https://github.com/bytedance/qemu/tree/vduse

V2 to V3:
- Fix some commit logs and print message

V1 to V2:
- Return and print error if validation fails in virtio-blk driver

Xie Yongji (4):
  block: Add a helper to validate the block size
  nbd: Use blk_validate_block_size() to validate block size
  loop: Use blk_validate_block_size() to validate block size
  virtio-blk: Use blk_validate_block_size() to validate block size

 drivers/block/loop.c       | 17 ++---------------
 drivers/block/nbd.c        |  3 ++-
 drivers/block/virtio_blk.c | 12 ++++++++++--
 include/linux/blkdev.h     |  8 ++++++++
 4 files changed, 22 insertions(+), 18 deletions(-)

-- 
2.11.0

[PATCH v3 1/4] block: Add a helper to validate the block size

[Xie Yongji]

There are some duplicated codes to validate the block
size in block drivers. This limitation actually comes
from block layer, so this patch tries to add a new block
layer helper for that.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 include/linux/blkdev.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 12b9dbcc980e..805cd02d7914 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -235,6 +235,14 @@ struct request {
 	void *end_io_data;
 };
 
+static inline int blk_validate_block_size(unsigned int bsize)
+{
+	if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
+		return -EINVAL;
+
+	return 0;
+}
+
 static inline bool blk_op_is_passthrough(unsigned int op)
 {
 	op &= REQ_OP_MASK;
-- 
2.11.0

[PATCH v3 2/4] nbd: Use blk_validate_block_size() to validate block size

[Xie Yongji]

Use the block layer helper to validate block size instead
of open coding it.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 drivers/block/nbd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1183f7872b71..3f58c3eb38b6 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -323,7 +323,8 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 {
 	if (!blksize)
 		blksize = 1u << NBD_DEF_BLKSIZE_BITS;
-	if (blksize < 512 || blksize > PAGE_SIZE || !is_power_of_2(blksize))
+
+	if (blk_validate_block_size(blksize))
 		return -EINVAL;
 
 	nbd->config->bytesize = bytesize;
-- 
2.11.0

[PATCH v3 3/4] loop: Use blk_validate_block_size() to validate block size

[Xie Yongji]

Remove loop_validate_block_size() and use the block layer helper
to validate block size.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 drivers/block/loop.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7bf4686af774..dfc72a1f6500 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -273,19 +273,6 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
 }
 
 /**
- * loop_validate_block_size() - validates the passed in block size
- * @bsize: size to validate
- */
-static int
-loop_validate_block_size(unsigned short bsize)
-{
-	if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
-		return -EINVAL;
-
-	return 0;
-}
-
-/**
  * loop_set_size() - sets device size and notifies userspace
  * @lo: struct loop_device to set the size for
  * @size: new size of the loop device
@@ -1236,7 +1223,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
 	}
 
 	if (config->block_size) {
-		error = loop_validate_block_size(config->block_size);
+		error = blk_validate_block_size(config->block_size);
 		if (error)
 			goto out_unlock;
 	}
@@ -1759,7 +1746,7 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
 	if (lo->lo_state != Lo_bound)
 		return -ENXIO;
 
-	err = loop_validate_block_size(arg);
+	err = blk_validate_block_size(arg);
 	if (err)
 		return err;
 
-- 
2.11.0

[PATCH v3 4/4] virtio-blk: Use blk_validate_block_size() to validate block size

[Xie Yongji]

The block layer can't support a block size larger than
page size yet. And a block size that's too small or
not a power of two won't work either. If a misconfigured
device presents an invalid block size in configuration space,
it will result in the kernel crash something like below:

[  506.154324] BUG: kernel NULL pointer dereference, address: 0000000000000008
[  506.160416] RIP: 0010:create_empty_buffers+0x24/0x100
[  506.174302] Call Trace:
[  506.174651]  create_page_buffers+0x4d/0x60
[  506.175207]  block_read_full_page+0x50/0x380
[  506.175798]  ? __mod_lruvec_page_state+0x60/0xa0
[  506.176412]  ? __add_to_page_cache_locked+0x1b2/0x390
[  506.177085]  ? blkdev_direct_IO+0x4a0/0x4a0
[  506.177644]  ? scan_shadow_nodes+0x30/0x30
[  506.178206]  ? lru_cache_add+0x42/0x60
[  506.178716]  do_read_cache_page+0x695/0x740
[  506.179278]  ? read_part_sector+0xe0/0xe0
[  506.179821]  read_part_sector+0x36/0xe0
[  506.180337]  adfspart_check_ICS+0x32/0x320
[  506.180890]  ? snprintf+0x45/0x70
[  506.181350]  ? read_part_sector+0xe0/0xe0
[  506.181906]  bdev_disk_changed+0x229/0x5c0
[  506.182483]  blkdev_get_whole+0x6d/0x90
[  506.183013]  blkdev_get_by_dev+0x122/0x2d0
[  506.183562]  device_add_disk+0x39e/0x3c0
[  506.184472]  virtblk_probe+0x3f8/0x79b [virtio_blk]
[  506.185461]  virtio_dev_probe+0x15e/0x1d0 [virtio]

So let's use a block layer helper to validate the block size.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 drivers/block/virtio_blk.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 303caf2d17d0..fd086179f980 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -815,9 +815,17 @@ static int virtblk_probe(struct virtio_device *vdev)
 	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
 				   struct virtio_blk_config, blk_size,
 				   &blk_size);
-	if (!err)
+	if (!err) {
+		err = blk_validate_block_size(blk_size);
+		if (err) {
+			dev_err(&vdev->dev,
+				"virtio_blk: invalid block size: 0x%x\n",
+				blk_size);
+			goto out_cleanup_disk;
+		}
+
 		blk_queue_logical_block_size(q, blk_size);
-	else
+	} else
 		blk_size = queue_logical_block_size(q);
 
 	/* Use topology information if available */
-- 
2.11.0

Re: [PATCH v3 4/4] virtio-blk: Use blk_validate_block_size() to validate block size

[Michael S. Tsirkin]

On Tue, Oct 26, 2021 at 10:40:15PM +0800, Xie Yongji wrote:
> The block layer can't support a block size larger than
> page size yet. And a block size that's too small or
> not a power of two won't work either. If a misconfigured
> device presents an invalid block size in configuration space,
> it will result in the kernel crash something like below:
> 
> [  506.154324] BUG: kernel NULL pointer dereference, address: 0000000000000008
> [  506.160416] RIP: 0010:create_empty_buffers+0x24/0x100
> [  506.174302] Call Trace:
> [  506.174651]  create_page_buffers+0x4d/0x60
> [  506.175207]  block_read_full_page+0x50/0x380
> [  506.175798]  ? __mod_lruvec_page_state+0x60/0xa0
> [  506.176412]  ? __add_to_page_cache_locked+0x1b2/0x390
> [  506.177085]  ? blkdev_direct_IO+0x4a0/0x4a0
> [  506.177644]  ? scan_shadow_nodes+0x30/0x30
> [  506.178206]  ? lru_cache_add+0x42/0x60
> [  506.178716]  do_read_cache_page+0x695/0x740
> [  506.179278]  ? read_part_sector+0xe0/0xe0
> [  506.179821]  read_part_sector+0x36/0xe0
> [  506.180337]  adfspart_check_ICS+0x32/0x320
> [  506.180890]  ? snprintf+0x45/0x70
> [  506.181350]  ? read_part_sector+0xe0/0xe0
> [  506.181906]  bdev_disk_changed+0x229/0x5c0
> [  506.182483]  blkdev_get_whole+0x6d/0x90
> [  506.183013]  blkdev_get_by_dev+0x122/0x2d0
> [  506.183562]  device_add_disk+0x39e/0x3c0
> [  506.184472]  virtblk_probe+0x3f8/0x79b [virtio_blk]
> [  506.185461]  virtio_dev_probe+0x15e/0x1d0 [virtio]
> 
> So let's use a block layer helper to validate the block size.
> 
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>

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


Please merge through the block tree because of the
dependency.

Jens can you pick this up?

> ---
>  drivers/block/virtio_blk.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 303caf2d17d0..fd086179f980 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -815,9 +815,17 @@ static int virtblk_probe(struct virtio_device *vdev)
>  	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
>  				   struct virtio_blk_config, blk_size,
>  				   &blk_size);
> -	if (!err)
> +	if (!err) {
> +		err = blk_validate_block_size(blk_size);
> +		if (err) {
> +			dev_err(&vdev->dev,
> +				"virtio_blk: invalid block size: 0x%x\n",
> +				blk_size);
> +			goto out_cleanup_disk;
> +		}
> +
>  		blk_queue_logical_block_size(q, blk_size);
> -	else
> +	} else
>  		blk_size = queue_logical_block_size(q);
>  
>  	/* Use topology information if available */
> -- 
> 2.11.0

Re: [PATCH v3 0/4] Add blk_validate_block_size() helper for drivers to validate block size

[Jens Axboe]

On Tue, 26 Oct 2021 22:40:11 +0800, Xie Yongji wrote:
> The block layer can't support the block size larger than
> page size yet, so driver needs to validate the block size
> before setting it. Now this validation is done in device drivers
> with some duplicated codes. This series tries to add a block
> layer helper for it and makes loop driver, nbd driver and
> virtio-blk driver use it.
> 
> [...]

Applied, thanks!

[1/4] block: Add a helper to validate the block size
      commit: 570b1cac477643cbf01a45fa5d018430a1fddbce
[2/4] nbd: Use blk_validate_block_size() to validate block size
      commit: c4318d6cd038472d13e08a54a9035863c8c160bd
[3/4] loop: Use blk_validate_block_size() to validate block size
      commit: af3c570fb0df422b4906ebd11c1bf363d89961d5
[4/4] virtio-blk: Use blk_validate_block_size() to validate block size
      commit: 57a13a5b8157d9a8606490aaa1b805bafe6c37e1

Best regards,
-- 
Jens Axboe