kernel/linux.git/drivers/block/nbd.c, branch v5.10.257

nbd: defer config unlock in nbd_genl_connect

2026-01-19T12:11:31+00:00

[ Upstream commit 1649714b930f9ea6233ce0810ba885999da3b5d4 ] There is one use-after-free warning when running NBD_CMD_CONNECT and NBD_CLEAR_SOCK: nbd_genl_connect nbd_alloc_and_init_config // config_refs=1 nbd_start_device // config_refs=2 set NBD_RT_HAS_CONFIG_REF open nbd // config_refs=3 recv_work done // config_refs=2 NBD_CLEAR_SOCK // config_refs=1 close nbd // config_refs=0 refcount_inc -> uaf ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 24 PID: 1014 at lib/refcount.c:25 refcount_warn_saturate+0x12e/0x290 nbd_genl_connect+0x16d0/0x1ab0 genl_family_rcv_msg_doit+0x1f3/0x310 genl_rcv_msg+0x44a/0x790 The issue can be easily reproduced by adding a small delay before refcount_inc(&nbd->config_refs) in nbd_genl_connect(): mutex_unlock(&nbd->config_lock); if (!ret) { set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags); + printk("before sleep\n"); + mdelay(5 * 1000); + printk("after sleep\n"); refcount_inc(&nbd->config_refs); nbd_connect_reply(info, nbd->index); } Fixes: e46c7287b1c2 ("nbd: add a basic netlink interface") Signed-off-by: Zheng Qixing Reviewed-by: Yu Kuai Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: defer config put in recv_work

2026-01-19T12:11:30+00:00

[ Upstream commit 9517b82d8d422d426a988b213fdd45c6b417b86d ] There is one uaf issue in recv_work when running NBD_CLEAR_SOCK and NBD_CMD_RECONFIGURE: nbd_genl_connect // conf_ref=2 (connect and recv_work A) nbd_open // conf_ref=3 recv_work A done // conf_ref=2 NBD_CLEAR_SOCK // conf_ref=1 nbd_genl_reconfigure // conf_ref=2 (trigger recv_work B) close nbd // conf_ref=1 recv_work B config_put // conf_ref=0 atomic_dec(&config->recv_threads); -> UAF Or only running NBD_CLEAR_SOCK: nbd_genl_connect // conf_ref=2 nbd_open // conf_ref=3 NBD_CLEAR_SOCK // conf_ref=2 close nbd nbd_release config_put // conf_ref=1 recv_work config_put // conf_ref=0 atomic_dec(&config->recv_threads); -> UAF Commit 87aac3a80af5 ("nbd: call nbd_config_put() before notifying the waiter") moved nbd_config_put() to run before waking up the waiter in recv_work, in order to ensure that nbd_start_device_ioctl() would not be woken up while nbd->task_recv was still uncleared. However, in nbd_start_device_ioctl(), after being woken up it explicitly calls flush_workqueue() to make sure all current works are finished. Therefore, there is no need to move the config put ahead of the wakeup. Move nbd_config_put() to the end of recv_work, so that the reference is held for the whole lifetime of the worker thread. This makes sure the config cannot be freed while recv_work is still running, even if clear + reconfigure interleave. In addition, we don't need to worry about recv_work dropping the last nbd_put (which causes deadlock): path A (netlink with NBD_CFLAG_DESTROY_ON_DISCONNECT): connect // nbd_refs=1 (trigger recv_work) open nbd // nbd_refs=2 NBD_CLEAR_SOCK close nbd nbd_release nbd_disconnect_and_put flush_workqueue // recv_work done nbd_config_put nbd_put // nbd_refs=1 nbd_put // nbd_refs=0 queue_work path B (netlink without NBD_CFLAG_DESTROY_ON_DISCONNECT): connect // nbd_refs=2 (trigger recv_work) open nbd // nbd_refs=3 NBD_CLEAR_SOCK // conf_refs=2 close nbd nbd_release nbd_config_put // conf_refs=1 nbd_put // nbd_refs=2 recv_work done // conf_refs=0, nbd_refs=1 rmmod // nbd_refs=0 Reported-by: syzbot+56fbf4c7ddf65e95c7cc@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6907edce.a70a0220.37351b.0014.GAE@google.com/T/ Fixes: 87aac3a80af5 ("nbd: make the config put is called before the notifying the waiter") Depends-on: e2daec488c57 ("nbd: Fix hungtask when nbd_config_put") Signed-off-by: Zheng Qixing Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply()

2026-01-19T12:11:30+00:00

[ Upstream commit 3fe1db626a56cdf259c348404f2c5429e2f065a1 ] Prepare to fix uaf in nbd_read_stat(), no functional changes. Signed-off-by: Yu Kuai Reviewed-by: Ming Lei Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20210916093350.1410403-7-yukuai3@huawei.com Signed-off-by: Jens Axboe Stable-dep-of: 9517b82d8d42 ("nbd: defer config put in recv_work") Signed-off-by: Sasha Levin

nbd: clean up return value checking of sock_xmit()

2026-01-19T12:11:30+00:00

[ Upstream commit f52c0e08237e7864a44311fc78bc9bf2e045611b ] Check if sock_xmit() return 0 is useless because it'll never return 0, comment it and remove such checkings. Signed-off-by: Yu Kuai Reviewed-by: Ming Lei Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20210916093350.1410403-6-yukuai3@huawei.com Signed-off-by: Jens Axboe Stable-dep-of: 9517b82d8d42 ("nbd: defer config put in recv_work") Signed-off-by: Sasha Levin

nbd: don't allow reconnect after disconnect

2025-03-13T11:46:44+00:00

[ Upstream commit 844b8cdc681612ff24df62cdefddeab5772fadf1 ] Following process can cause nbd_config UAF: 1) grab nbd_config temporarily; 2) nbd_genl_disconnect() flush all recv_work() and release the initial reference: nbd_genl_disconnect nbd_disconnect_and_put nbd_disconnect flush_workqueue(nbd->recv_workq) if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...)) nbd_config_put -> due to step 1), reference is still not zero 3) nbd_genl_reconfigure() queue recv_work() again; nbd_genl_reconfigure config = nbd_get_config_unlocked(nbd) if (!config) -> succeed if (!test_bit(NBD_RT_BOUND, ...)) -> succeed nbd_reconnect_socket queue_work(nbd->recv_workq, &args->work) 4) step 1) release the reference; 5) Finially, recv_work() will trigger UAF: recv_work nbd_config_put(nbd) -> nbd_config is freed atomic_dec(&config->recv_threads) -> UAF Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so that nbd_genl_reconfigure() will fail. Fixes: b7aa3d39385d ("nbd: add a reconfigure netlink command") Reported-by: syzbot+6b0df248918b92c33e6a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/675bfb65.050a0220.1a2d0d.0006.GAE@google.com/ Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250103092859.3574648-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: null check for nla_nest_start

2024-03-26T22:21:47+00:00

[ Upstream commit 31edf4bbe0ba27fd03ac7d87eb2ee3d2a231af6d ] nla_nest_start() may fail and return NULL. Insert a check and set errno based on other call sites within the same source code. Signed-off-by: Navid Emamdoost Reviewed-by: Michal Kubecek Fixes: 47d902b90a32 ("nbd: add a status netlink command") Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20240218042534.it.206-kees@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: Add the maximum limit of allocated index in nbd_dev_add

2023-07-27T06:44:36+00:00

[ Upstream commit f12bc113ce904777fd6ca003b473b427782b3dde ] If the index allocated by idr_alloc greater than MINORMASK >> part_shift, the device number will overflow, resulting in failure to create a block device. Fix it by imiting the size of the max allocation. Signed-off-by: Zhong Jinghua Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230605122159.2134384-1-zhongjinghua@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: Fix debugfs_create_dir error checking

2023-06-09T08:30:08+00:00

[ Upstream commit 4913cfcf014c95f0437db2df1734472fd3e15098 ] The debugfs_create_dir function returns ERR_PTR in case of error, and the only correct way to check if an error occurred is 'IS_ERR' inline function. This patch will replace the null-comparison with IS_ERR. Signed-off-by: Ivan Orlov Link: https://lore.kernel.org/r/20230512130533.98709-1-ivan.orlov0322@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: fix possible overflow on 'first_minor' in nbd_dev_add()

2023-02-25T10:55:04+00:00

commit 858f1bf65d3d9c00b5e2d8ca87dc79ed88267c98 upstream. When 'index' is a big numbers, it may become negative which forced to 'int'. then 'index << part_shift' might overflow to a positive value that is not greater than '0xfffff', then sysfs might complains about duplicate creation. Because of this, move the 'index' judgment to the front will fix it and be better. Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices") Fixes: 940c264984fd ("nbd: fix possible overflow for 'first_minor' in nbd_dev_add()") Signed-off-by: Zhang Wensheng Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220521073749.3146892-6-yukuai3@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Wen Yang Signed-off-by: Greg Kroah-Hartman

nbd: fix possible overflow for 'first_minor' in nbd_dev_add()

2023-02-25T10:55:04+00:00

commit 940c264984fd1457918393c49674f6b39ee16506 upstream. If 'part_shift' is not zero, then 'index << part_shift' might overflow to a value that is not greater than '0xfffff', then sysfs might complains about duplicate creation. Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices") Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20211102015237.2309763-3-yebin10@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Wen Yang Signed-off-by: Greg Kroah-Hartman