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author | Yu Kuai <yukuai3@huawei.com> | 2022-05-21 15:37:45 +0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-14 16:59:38 +0200 |
commit | 2573f2375b64280be977431701ed5d33b75b9ad0 (patch) | |
tree | 7f20a3268191a2bc75c6db459b1f1f0ef66a26e2 /lib | |
parent | 013a79f1b5c89290e2e97f1ebf14b14e0cf5fe5c (diff) | |
download | linux-stable-2573f2375b64280be977431701ed5d33b75b9ad0.tar.gz linux-stable-2573f2375b64280be977431701ed5d33b75b9ad0.tar.bz2 linux-stable-2573f2375b64280be977431701ed5d33b75b9ad0.zip |
nbd: fix race between nbd_alloc_config() and module removal
[ Upstream commit c55b2b983b0fa012942c3eb16384b2b722caa810 ]
When nbd module is being removing, nbd_alloc_config() may be
called concurrently by nbd_genl_connect(), although try_module_get()
will return false, but nbd_alloc_config() doesn't handle it.
The race may lead to the leak of nbd_config and its related
resources (e.g, recv_workq) and oops in nbd_read_stat() due
to the unload of nbd module as shown below:
BUG: kernel NULL pointer dereference, address: 0000000000000040
Oops: 0000 [#1] SMP PTI
CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: knbd16-recv recv_work [nbd]
RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd]
Call Trace:
recv_work+0x3b/0xb0 [nbd]
process_one_work+0x1ed/0x390
worker_thread+0x4a/0x3d0
kthread+0x12a/0x150
ret_from_fork+0x22/0x30
Fixing it by checking the return value of try_module_get()
in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV),
assign nbd->config only when nbd_alloc_config() succeeds to ensure
the value of nbd->config is binary (valid or NULL).
Also adding a debug message to check the reference counter
of nbd_config during module removal.
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/20220521073749.3146892-3-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'lib')
0 files changed, 0 insertions, 0 deletions