6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Li Lingfeng lilingfeng3@huawei.com
[ Upstream commit 327462725b0f759f093788dfbcb2f1fd132f956b ]
Commit 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk") cleans up disk by blk_cleanup_disk() and it won't set disk->private_data as NULL as before. UAF may be triggered in nbd_open() if someone tries to open nbd device right after nbd_put() since nbd has been free in nbd_dev_remove().
Fix this by implementing ->free_disk and free private data in it.
Fixes: 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk") Signed-off-by: Li Lingfeng lilingfeng3@huawei.com Reviewed-by: Josef Bacik josef@toxicpanda.com Link: https://lore.kernel.org/r/20231107103435.2074904-1-lilingfeng@huaweicloud.co... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/nbd.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 8576d696c7a22..f6a9eda9fbb20 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -250,7 +250,6 @@ static void nbd_dev_remove(struct nbd_device *nbd) struct gendisk *disk = nbd->disk;
del_gendisk(disk); - put_disk(disk); blk_mq_free_tag_set(&nbd->tag_set);
/* @@ -261,7 +260,7 @@ static void nbd_dev_remove(struct nbd_device *nbd) idr_remove(&nbd_index_idr, nbd->index); mutex_unlock(&nbd_index_mutex); destroy_workqueue(nbd->recv_workq); - kfree(nbd); + put_disk(disk); }
static void nbd_dev_remove_work(struct work_struct *work) @@ -1609,6 +1608,13 @@ static void nbd_release(struct gendisk *disk) nbd_put(nbd); }
+static void nbd_free_disk(struct gendisk *disk) +{ + struct nbd_device *nbd = disk->private_data; + + kfree(nbd); +} + static const struct block_device_operations nbd_fops = { .owner = THIS_MODULE, @@ -1616,6 +1622,7 @@ static const struct block_device_operations nbd_fops = .release = nbd_release, .ioctl = nbd_ioctl, .compat_ioctl = nbd_ioctl, + .free_disk = nbd_free_disk, };
#if IS_ENABLED(CONFIG_DEBUG_FS)