[PATCH 4.9 1/2] block: Add a helper to validate the block size

[PATCH 4.9 1/2] block: Add a helper to validate the block size

[Lee Jones]

From: Xie Yongji <xieyongji@bytedance.com>

[ Upstream commit 570b1cac477643cbf01a45fa5d018430a1fddbce ]

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>
Link: https://lore.kernel.org/r/20211026144015.188-2-xieyongji@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 include/linux/blkdev.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 848aab6c69823..8050724065524 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -49,6 +49,14 @@ struct pr_ops;
 
 typedef void (rq_end_io_fn)(struct request *, int);
 
+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;
+}
+
 #define BLK_RL_SYNCFULL		(1U << 0)
 #define BLK_RL_ASYNCFULL	(1U << 1)
 
-- 
2.35.1.1021.g381101b075-goog

[PATCH 4.9 2/2] virtio-blk: Use blk_validate_block_size() to validate block size

[Lee Jones]

From: Xie Yongji <xieyongji@bytedance.com>

[ Upstream commit 57a13a5b8157d9a8606490aaa1b805bafe6c37e1 ]

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>
Link: https://lore.kernel.org/r/20211026144015.188-5-xieyongji@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 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 302260e9002c7..45bd0d7d6a942 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -692,9 +692,17 @@ 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_free_tags;
+		}
+
 		blk_queue_logical_block_size(q, blk_size);
-	else
+	} else
 		blk_size = queue_logical_block_size(q);
 
 	/* Use topology information if available */
-- 
2.35.1.1021.g381101b075-goog