kernel/linux.git/drivers/block/nbd.c, branch v4.14.286

nbd: fix io hung while disconnecting device

2022-06-14T14:54:01+00:00

[ Upstream commit 09dadb5985023e27d4740ebd17e6fea4640110e5 ] In our tests, "qemu-nbd" triggers a io hung: INFO: task qemu-nbd:11445 blocked for more than 368 seconds. Not tainted 5.18.0-rc3-next-20220422-00003-g2176915513ca #884 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:qemu-nbd state:D stack: 0 pid:11445 ppid: 1 flags:0x00000000 Call Trace: __schedule+0x480/0x1050 ? _raw_spin_lock_irqsave+0x3e/0xb0 schedule+0x9c/0x1b0 blk_mq_freeze_queue_wait+0x9d/0xf0 ? ipi_rseq+0x70/0x70 blk_mq_freeze_queue+0x2b/0x40 nbd_add_socket+0x6b/0x270 [nbd] nbd_ioctl+0x383/0x510 [nbd] blkdev_ioctl+0x18e/0x3e0 __x64_sys_ioctl+0xac/0x120 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fd8ff706577 RSP: 002b:00007fd8fcdfebf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000040000000 RCX: 00007fd8ff706577 RDX: 000000000000000d RSI: 000000000000ab00 RDI: 000000000000000f RBP: 000000000000000f R08: 000000000000fbe8 R09: 000055fe497c62b0 R10: 00000002aff20000 R11: 0000000000000246 R12: 000000000000006d R13: 0000000000000000 R14: 00007ffe82dc5e70 R15: 00007fd8fcdff9c0 "qemu-ndb -d" will call ioctl 'NBD_DISCONNECT' first, however, following message was found: block nbd0: Send disconnect failed -32 Which indicate that something is wrong with the server. Then, "qemu-nbd -d" will call ioctl 'NBD_CLEAR_SOCK', however ioctl can't clear requests after commit 2516ab1543fd("nbd: only clear the queue on device teardown"). And in the meantime, request can't complete through timeout because nbd_xmit_timeout() will always return 'BLK_EH_RESET_TIMER', which means such request will never be completed in this situation. Now that the flag 'NBD_CMD_INFLIGHT' can make sure requests won't complete multiple times, switch back to call nbd_clear_sock() in nbd_clear_sock_ioctl(), so that inflight requests can be cleared. Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220521073749.3146892-5-yukuai3@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: fix race between nbd_alloc_config() and module removal

2022-06-14T14:54:01+00:00

[ 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 Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220521073749.3146892-3-yukuai3@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: call genl_unregister_family() first in nbd_cleanup()

2022-06-14T14:54:01+00:00

[ 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 Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220521073749.3146892-2-yukuai3@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: freeze the queue while we're adding connections

2021-02-03T22:22:20+00:00

commit b98e762e3d71e893b221f871825dc64694cfb258 upstream. When setting up a device, we can krealloc the config->socks array to add new sockets to the configuration. However if we happen to get a IO request in at this point even though we aren't setup we could hit a UAF, as we deref config->socks without any locking, assuming that the configuration was setup already and that ->socks is safe to access it as we have a reference on the configuration. But there's nothing really preventing IO from occurring at this point of the device setup, we don't want to incur the overhead of a lock to access ->socks when it will never change while the device is running. To fix this UAF scenario simply freeze the queue if we are adding sockets. This will protect us from this particular case without adding any additional overhead for the normal running case. Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

nbd: fix a block_device refcount leak in nbd_release

2020-11-18T17:27:56+00:00

[ Upstream commit 2bd645b2d3f0bacadaa6037f067538e1cd4e42ef ] bdget_disk needs to be paired with bdput to not leak a reference on the block device inode. Fixes: 08ba91ee6e2c ("nbd: Add the nbd NBD_DISCONNECT_ON_CLOSE config flag.") Signed-off-by: Christoph Hellwig Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: don't update block size after device is started

2020-11-18T17:27:52+00:00

[ Upstream commit b40813ddcd6bf9f01d020804e4cb8febc480b9e4 ] Mounted NBD device can be resized, one use case is rbd-nbd. Fix the issue by setting up default block size, then not touch it in nbd_size_update() any more. This kind of usage is aligned with loop which has same use case too. Cc: stable@vger.kernel.org Fixes: c8a83a6b54d0 ("nbd: Use set_blocksize() to set device blocksize") Reported-by: lining Signed-off-by: Ming Lei Cc: Josef Bacik Cc: Jan Kara Tested-by: lining Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: make the config put is called before the notifying the waiter

2020-11-05T10:06:58+00:00

[ Upstream commit 87aac3a80af5cbad93e63250e8a1e19095ba0d30 ] There has one race case for ceph's rbd-nbd tool. When do mapping it may fail with EBUSY from ioctl(nbd, NBD_DO_IT), but actually the nbd device has already unmaped. It dues to if just after the wake_up(), the recv_work() is scheduled out and defers calling the nbd_config_put(), though the map process has exited the "nbd->recv_task" is not cleared. Signed-off-by: Xiubo Li Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: Fix memory leak in nbd_add_socket

2020-07-22T07:22:17+00:00

[ Upstream commit 579dd91ab3a5446b148e7f179b6596b270dace46 ] When adding first socket to nbd, if nsock's allocation failed, the data structure member "config->socks" was reallocated, but the data structure member "config->num_connections" was not updated. A memory leak will occur then because the function "nbd_config_put" will free "config->socks" only when "config->num_connections" is not zero. Fixes: 03bf73c315ed ("nbd: prevent memory leak") Reported-by: syzbot+934037347002901b8d2a@syzkaller.appspotmail.com Signed-off-by: Zheng Bin Reviewed-by: Eric Biggers Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: add a flush_workqueue in nbd_start_device

2020-02-28T15:35:58+00:00

[ Upstream commit 5c0dd228b5fc30a3b732c7ae2657e0161ec7ed80 ] When kzalloc fail, may cause trying to destroy the workqueue from inside the workqueue. If num_connections is m (2 < m), and NO.1 ~ NO.n (1 < n < m) kzalloc are successful. The NO.(n + 1) failed. Then, nbd_start_device will return ENOMEM to nbd_start_device_ioctl, and nbd_start_device_ioctl will return immediately without running flush_workqueue. However, we still have n recv threads. If nbd_release run first, recv threads may have to drop the last config_refs and try to destroy the workqueue from inside the workqueue. To fix it, add a flush_workqueue in nbd_start_device. Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs") Signed-off-by: Sun Ke Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

nbd: fix shutdown and recv work deadlock v2

2019-12-31T11:38:07+00:00

commit 1c05839aa973cfae8c3db964a21f9c0eef8fcc21 upstream. This fixes a regression added with: commit e9e006f5fcf2bab59149cb38a48a4817c1b538b4 Author: Mike Christie Date: Sun Aug 4 14:10:06 2019 -0500 nbd: fix max number of supported devs where we can deadlock during device shutdown. The problem occurs if the recv_work's nbd_config_put occurs after nbd_start_device_ioctl has returned and the userspace app has droppped its reference via closing the device and running nbd_release. The recv_work nbd_config_put call would then drop the refcount to zero and try to destroy the config which would try to do destroy_workqueue from the recv work. This patch just has nbd_start_device_ioctl do a flush_workqueue when it wakes so we know after the ioctl returns running works have exited. This also fixes a possible race where we could try to reuse the device while old recv_works are still running. Cc: stable@vger.kernel.org Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs") Signed-off-by: Mike Christie Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman