From: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
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@xxxxxxxxxx>
---
v1->v2: Implemente ->free_disk and free nbd in it instead of setting
disk->private_data as NULL before free nbd.
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 800f131222fc..855fdf5c3b4e 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)
@@ -1608,6 +1607,13 @@ 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,
@@ -1615,6 +1621,7 @@ 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)
--
2.31.1
