diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2022-05-21 15:37:44 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-14 18:41:39 +0200 |
| commit | 6f505bbb8063fd3a238a4239d2d8c165e5279f6f (patch) | |
| tree | 597b93f20ed52c5d761daa31ea990e381de6de9f /drivers | |
| parent | d05317ba12b128c4cce0549006f71819b18706e6 (diff) | |
nbd: call genl_unregister_family() first in nbd_cleanup()
[ Upstream commit 06c4da89c24e7023ea448cadf8e9daf06a0aae6e ]
Otherwise there may be race between module removal and the handling of
netlink command, which can lead to the oops as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000098
Oops: 0002 [#1] SMP PTI
CPU: 1 PID: 31299 Comm: nbd-client Tainted: G E 5.14.0-rc4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:down_write+0x1a/0x50
Call Trace:
start_creating+0x89/0x130
debugfs_create_dir+0x1b/0x130
nbd_start_device+0x13d/0x390 [nbd]
nbd_genl_connect+0x42f/0x748 [nbd]
genl_family_rcv_msg_doit.isra.0+0xec/0x150
genl_rcv_msg+0xe5/0x1e0
netlink_rcv_skb+0x55/0x100
genl_rcv+0x29/0x40
netlink_unicast+0x1a8/0x250
netlink_sendmsg+0x21b/0x430
____sys_sendmsg+0x2a4/0x2d0
___sys_sendmsg+0x81/0xc0
__sys_sendmsg+0x62/0xb0
__x64_sys_sendmsg+0x1f/0x30
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
Modules linked in: nbd(E-)
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20220521073749.3146892-2-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/block/nbd.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index ed678037ba6d..b4d309af27dd 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -2544,6 +2544,12 @@ static void __exit nbd_cleanup(void) struct nbd_device *nbd; LIST_HEAD(del_list); + /* + * Unregister netlink interface prior to waiting + * for the completion of netlink commands. + */ + genl_unregister_family(&nbd_genl_family); + nbd_dbg_close(); mutex_lock(&nbd_index_mutex); @@ -2562,7 +2568,6 @@ static void __exit nbd_cleanup(void) destroy_workqueue(nbd_del_wq); idr_destroy(&nbd_index_idr); - genl_unregister_family(&nbd_genl_family); unregister_blkdev(NBD_MAJOR, "nbd"); } |