[PATCH AUTOSEL 6.6 30/35] null_blk: fix validation of block size

[Sasha Levin]

From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>

[ Upstream commit c462ecd659b5fce731f1d592285832fd6ad54053 ]

Block size should be between 512 and PAGE_SIZE and be a power of 2. The current
check does not validate this, so update the check.

Without this patch, null_blk would Oops due to a null pointer deref when
loaded with bs=1536 [1].

Link: https://lore.kernel.org/all/87wmn8mocd.fsf@xxxxxxxxxxxx/

Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240603192645.977968-1-nmi@xxxxxxxxxxxx
[axboe: remove unnecessary braces and != 0 check]
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/block/null_blk/main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 561706fc2cd8e..f1b7d7fdffec8 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -2013,8 +2013,8 @@ static int null_validate_conf(struct nullb_device *dev)
 		return -EINVAL;
 	}
 
-	dev->blocksize = round_down(dev->blocksize, 512);
-	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
+	if (blk_validate_block_size(dev->blocksize))
+		return -EINVAL;
 
 	if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
 		if (dev->submit_queues != nr_online_nodes)
-- 
2.43.0