[syzbot] possible deadlock in nci_set_local_general_bytes

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syzbot

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Nov 14, 2022, 12:43:49 PM11/14/22
to da...@davemloft.net, edum...@google.com, krzysztof...@linaro.org, ku...@kernel.org, li...@zju.edu.cn, linux-...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=119413e1880000
kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1097e935880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177b5b15880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/82aa7741098d/disk-1621b6ea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f6be08c4e4c2/vmlinux-1621b6ea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/296b6946258a/Image-1621b6ea.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8768e9...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc4-syzkaller-31872-g1621b6eaebf7 #0 Not tainted
------------------------------------------------------
syz-executor402/3146 is trying to acquire lock:
ffff0000cad76350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_request net/nfc/nci/core.c:148 [inline]
ffff0000cad76350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_set_local_general_bytes+0xbc/0x480 net/nfc/nci/core.c:774

but task is already holding lock:
ffff0000cad73d18 (&genl_data->genl_data_mutex){+.+.}-{3:3}, at: nfc_genl_start_poll+0xc4/0x174 net/nfc/netlink.c:826

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&genl_data->genl_data_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nfc_urelease_event_work+0x88/0x16c net/nfc/netlink.c:1811
process_one_work+0x2d8/0x504 kernel/workqueue.c:2289
worker_thread+0x340/0x610 kernel/workqueue.c:2436
kthread+0x12c/0x158 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:863

-> #2 (nfc_devlist_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nfc_register_device+0x34/0x208 net/nfc/core.c:1116
nci_register_device+0x338/0x3b0 net/nfc/nci/core.c:1256
virtual_ncidev_open+0x6c/0xd8 drivers/nfc/virtual_ncidev.c:146
misc_open+0x1b8/0x200 drivers/char/misc.c:143
chrdev_open+0x2b4/0x2e8 fs/char_dev.c:414
do_dentry_open+0x364/0x748 fs/open.c:882
vfs_open+0x38/0x48 fs/open.c:1013
do_open fs/namei.c:3557 [inline]
path_openat+0xe34/0x11c4 fs/namei.c:3713
do_filp_open+0xdc/0x1b8 fs/namei.c:3740
do_sys_openat2+0xb8/0x22c fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__arm64_sys_openat+0xb0/0xe0 fs/open.c:1337
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #1 (nci_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
virtual_nci_close+0x28/0x58 drivers/nfc/virtual_ncidev.c:44
nci_open_device+0x414/0x518 net/nfc/nci/core.c:544
nci_dev_up+0x20/0x30 net/nfc/nci/core.c:631
nfc_dev_up+0xcc/0x1b0 net/nfc/core.c:118
nfc_genl_dev_up+0x40/0x78 net/nfc/netlink.c:770
genl_family_rcv_msg_doit net/netlink/genetlink.c:756 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
genl_rcv_msg+0x458/0x4f4 net/netlink/genetlink.c:850
netlink_rcv_skb+0xe8/0x1d4 net/netlink/af_netlink.c:2540
genl_rcv+0x38/0x50 net/netlink/genetlink.c:861
netlink_unicast_kernel+0xfc/0x1dc net/netlink/af_netlink.c:1319
netlink_unicast+0x164/0x248 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x484/0x584 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
____sys_sendmsg+0x2f8/0x440 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x1ac/0x228 net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x2c/0x3c net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (&ndev->req_lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nci_request net/nfc/nci/core.c:148 [inline]
nci_set_local_general_bytes+0xbc/0x480 net/nfc/nci/core.c:774
nci_start_poll+0x1e8/0x474 net/nfc/nci/core.c:838
nfc_start_poll+0xfc/0x170 net/nfc/core.c:225
nfc_genl_start_poll+0xd4/0x174 net/nfc/netlink.c:828
genl_family_rcv_msg_doit net/netlink/genetlink.c:756 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
genl_rcv_msg+0x458/0x4f4 net/netlink/genetlink.c:850
netlink_rcv_skb+0xe8/0x1d4 net/netlink/af_netlink.c:2540
genl_rcv+0x38/0x50 net/netlink/genetlink.c:861
netlink_unicast_kernel+0xfc/0x1dc net/netlink/af_netlink.c:1319
netlink_unicast+0x164/0x248 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x484/0x584 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
____sys_sendmsg+0x2f8/0x440 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x1ac/0x228 net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x2c/0x3c net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
&ndev->req_lock --> nfc_devlist_mutex --> &genl_data->genl_data_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&genl_data->genl_data_mutex);
lock(nfc_devlist_mutex);
lock(&genl_data->genl_data_mutex);
lock(&ndev->req_lock);

*** DEADLOCK ***

4 locks held by syz-executor402/3146:
#0: ffff80000d7c9268 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80000d7c9178 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80000d7c9178 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x80/0x4f4 net/netlink/genetlink.c:848
#2: ffff0000cad73d18 (&genl_data->genl_data_mutex){+.+.}-{3:3}, at: nfc_genl_start_poll+0xc4/0x174 net/nfc/netlink.c:826
#3: ffff0000cad73900 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:835 [inline]
#3: ffff0000cad73900 (&dev->mutex){....}-{3:3}, at: nfc_start_poll+0x5c/0x170 net/nfc/core.c:208

stack backtrace:
CPU: 0 PID: 3146 Comm: syz-executor402 Not tainted 6.1.0-rc4-syzkaller-31872-g1621b6eaebf7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nci_request net/nfc/nci/core.c:148 [inline]
nci_set_local_general_bytes+0xbc/0x480 net/nfc/nci/core.c:774
nci_start_poll+0x1e8/0x474 net/nfc/nci/core.c:838
nfc_start_poll+0xfc/0x170 net/nfc/core.c:225
nfc_genl_start_poll+0xd4/0x174 net/nfc/netlink.c:828
genl_family_rcv_msg_doit net/netlink/genetlink.c:756 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
genl_rcv_msg+0x458/0x4f4 net/netlink/genetlink.c:850
netlink_rcv_skb+0xe8/0x1d4 net/netlink/af_netlink.c:2540
genl_rcv+0x38/0x50 net/netlink/genetlink.c:861
netlink_unicast_kernel+0xfc/0x1dc net/netlink/af_netlink.c:1319
netlink_unicast+0x164/0x248 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x484/0x584 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
____sys_sendmsg+0x2f8/0x440 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x1ac/0x228 net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x2c/0x3c net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
nci: __nci_request: wait_for_completion_interruptible_timeout failed -512
nci: nci_start_poll: failed to set local general bytes
nci: __nci_request: wait_for_completion_interruptible_timeout failed 0


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Hillf Danton

unread,
Nov 14, 2022, 10:17:30 PM11/14/22
to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 14 Nov 2022 09:43:48 -0800
> syzbot found the following issue on:
>
> HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=119413e1880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
> dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1097e935880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177b5b15880000

Roll back in case of init failure without the req_lock held in a bid to
break the lock chain.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 1621b6eaebf7

--- x/net/nfc/nci/core.c
+++ c/net/nfc/nci/core.c
@@ -541,8 +541,10 @@ static int nci_open_device(struct nci_de
skb_queue_purge(&ndev->rx_q);
skb_queue_purge(&ndev->tx_q);

- ndev->ops->close(ndev);
ndev->flags = 0;
+ mutex_unlock(&ndev->req_lock);
+ ndev->ops->close(ndev);
+ return rc;
}

done:
--

syzbot

unread,
Nov 15, 2022, 3:40:28 AM11/15/22
to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in virtual_nci_close

nci: __nci_request: wait_for_completion_interruptible_timeout failed -512
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc4-syzkaller-00039-g1621b6eaebf7-dirty #0 Not tainted
------------------------------------------------------
syz-executor.0/4106 is trying to acquire lock:
ffff80000d5eaae0 (nci_mutex){+.+.}-{3:3}, at: virtual_nci_close+0x28/0x58 drivers/nfc/virtual_ncidev.c:44

but task is already holding lock:
ffff0000cb1f4350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x74/0x2b4 net/nfc/nci/core.c:562

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ndev->req_lock){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nci_request net/nfc/nci/core.c:148 [inline]
nci_set_local_general_bytes+0xbc/0x480 net/nfc/nci/core.c:776
nci_start_poll+0x1e8/0x474 net/nfc/nci/core.c:840
-> #2 (&genl_data->genl_data_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nfc_urelease_event_work+0x88/0x16c net/nfc/netlink.c:1811
process_one_work+0x2d8/0x504 kernel/workqueue.c:2289
worker_thread+0x340/0x610 kernel/workqueue.c:2436
kthread+0x12c/0x158 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:863

-> #1 (nfc_devlist_mutex){+.+.}-{3:3}:
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
nfc_register_device+0x34/0x208 net/nfc/core.c:1116
nci_register_device+0x338/0x3b0 net/nfc/nci/core.c:1258
virtual_ncidev_open+0x6c/0xd8 drivers/nfc/virtual_ncidev.c:146
misc_open+0x1b8/0x200 drivers/char/misc.c:143
chrdev_open+0x2b4/0x2e8 fs/char_dev.c:414
do_dentry_open+0x364/0x748 fs/open.c:882
vfs_open+0x38/0x48 fs/open.c:1013
do_open fs/namei.c:3557 [inline]
path_openat+0xe34/0x11c4 fs/namei.c:3713
do_filp_open+0xdc/0x1b8 fs/namei.c:3740
do_sys_openat2+0xb8/0x22c fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__arm64_sys_openat+0xb0/0xe0 fs/open.c:1337
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (nci_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
virtual_nci_close+0x28/0x58 drivers/nfc/virtual_ncidev.c:44
nci_close_device+0x188/0x2b4 net/nfc/nci/core.c:594
nci_unregister_device+0x3c/0x100 net/nfc/nci/core.c:1293
virtual_ncidev_close+0x70/0xb0 drivers/nfc/virtual_ncidev.c:166
__fput+0x198/0x3e4 fs/file_table.c:320
____fput+0x20/0x30 fs/file_table.c:348
task_work_run+0x100/0x148 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
nci_mutex --> &genl_data->genl_data_mutex --> &ndev->req_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ndev->req_lock);
lock(&genl_data->genl_data_mutex);
lock(&ndev->req_lock);
lock(nci_mutex);

*** DEADLOCK ***

1 lock held by syz-executor.0/4106:
#0: ffff0000cb1f4350 (&ndev->req_lock){+.+.}-{3:3}, at: nci_close_device+0x74/0x2b4 net/nfc/nci/core.c:562

stack backtrace:
CPU: 1 PID: 4106 Comm: syz-executor.0 Not tainted 6.1.0-rc4-syzkaller-00039-g1621b6eaebf7-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
virtual_nci_close+0x28/0x58 drivers/nfc/virtual_ncidev.c:44
nci_close_device+0x188/0x2b4 net/nfc/nci/core.c:594
nci_unregister_device+0x3c/0x100 net/nfc/nci/core.c:1293
virtual_ncidev_close+0x70/0xb0 drivers/nfc/virtual_ncidev.c:166
__fput+0x198/0x3e4 fs/file_table.c:320
____fput+0x20/0x30 fs/file_table.c:348
task_work_run+0x100/0x148 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584


Tested on:

commit: 1621b6ea Merge branch 'for-next/fixes' into for-kernelci
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=163ba9c1880000
kernel config: https://syzkaller.appspot.com/x/.config?x=699b4d125fc2883
dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch: https://syzkaller.appspot.com/x/patch.diff?x=11f33185880000

Hillf Danton

unread,
Nov 15, 2022, 4:18:42 AM11/15/22
to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 14 Nov 2022 09:43:48 -0800
> syzbot found the following issue on:
>
> HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=119413e1880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
> dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1097e935880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177b5b15880000

In the open path, register nci device without mci_mutex held in bid to break
the lock chain.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 1621b6eaebf7

--- x/drivers/nfc/virtual_ncidev.c
+++ y/drivers/nfc/virtual_ncidev.c
@@ -15,6 +15,7 @@

enum virtual_ncidev_mode {
virtual_ncidev_enabled,
+ virtual_ncidev_enabling,
virtual_ncidev_disabled,
virtual_ncidev_disabling,
};
@@ -128,6 +129,7 @@ static ssize_t virtual_ncidev_write(stru

static int virtual_ncidev_open(struct inode *inode, struct file *file)
{
+ struct nci_dev *new;
int ret = 0;

mutex_lock(&nci_mutex);
@@ -135,24 +137,27 @@ static int virtual_ncidev_open(struct in
mutex_unlock(&nci_mutex);
return -EBUSY;
}
+ state = virtual_ncidev_enabling;
+ mutex_unlock(&nci_mutex);

- ndev = nci_allocate_device(&virtual_nci_ops, VIRTUAL_NFC_PROTOCOLS,
- 0, 0);
- if (!ndev) {
- mutex_unlock(&nci_mutex);
- return -ENOMEM;
+ ret = -ENOMEM;
+ new = nci_allocate_device(&virtual_nci_ops, VIRTUAL_NFC_PROTOCOLS, 0, 0);
+ if (new) {
+ ret = nci_register_device(new);
+ if (ret)
+ nci_free_device(new);
}

- ret = nci_register_device(ndev);
- if (ret < 0) {
- nci_free_device(ndev);
- mutex_unlock(&nci_mutex);
- return ret;
+ mutex_lock(&nci_mutex);
+ if (ret)
+ state = virtual_ncidev_disabled;
+ else {
+ ndev = new;
+ state = virtual_ncidev_enabled;
}
- state = virtual_ncidev_enabled;
mutex_unlock(&nci_mutex);

- return 0;
+ return ret;
}

static int virtual_ncidev_close(struct inode *inode, struct file *file)
@@ -167,9 +172,9 @@ static int virtual_ncidev_close(struct i
nci_free_device(ndev);

mutex_lock(&nci_mutex);
+ state = virtual_ncidev_disabled;
}

- state = virtual_ncidev_disabled;
mutex_unlock(&nci_mutex);

return 0;
--

Dmitry Vyukov

unread,
Nov 15, 2022, 4:35:53 AM11/15/22
to Hillf Danton, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On Tue, 15 Nov 2022 at 10:18, Hillf Danton <hda...@sina.com> wrote:
>
> On 14 Nov 2022 09:43:48 -0800
> > syzbot found the following issue on:
> >
> > HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci
> > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> > console output: https://syzkaller.appspot.com/x/log.txt?x=119413e1880000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
> > dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
> > userspace arch: arm64
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1097e935880000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177b5b15880000
>
> In the open path, register nci device without mci_mutex held in bid to break
> the lock chain.

This should be fixed by the following commit when/if it's merged. The
commit removes nci_mutex.

nfc: Allow to create multiple virtual nci devices
https://lore.kernel.org/all/20221104170422....@google.com/
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bug...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20221115091825.2381-1-hdanton%40sina.com.

syzbot

unread,
Nov 15, 2022, 4:50:24 AM11/15/22
to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+8768e9...@syzkaller.appspotmail.com

Tested on:

commit: 1621b6ea Merge branch 'for-next/fixes' into for-kernelci
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12ced5a5880000
kernel config: https://syzkaller.appspot.com/x/.config?x=699b4d125fc2883
dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch: https://syzkaller.appspot.com/x/patch.diff?x=133ba9c1880000

Note: testing is done by a robot and is best-effort only.

Dmitry Vyukov

unread,
Nov 22, 2022, 8:07:33 AM11/22/22
to Hillf Danton, syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On Tue, 15 Nov 2022 at 10:35, Dmitry Vyukov <dvy...@google.com> wrote:
>
> On Tue, 15 Nov 2022 at 10:18, Hillf Danton <hda...@sina.com> wrote:
> >
> > On 14 Nov 2022 09:43:48 -0800
> > > syzbot found the following issue on:
> > >
> > > HEAD commit: 1621b6eaebf7 Merge branch 'for-next/fixes' into for-kernelci
> > > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=119413e1880000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=8768e9ec924b08e63f82
> > > userspace arch: arm64
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1097e935880000
> > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=177b5b15880000
> >
> > In the open path, register nci device without mci_mutex held in bid to break
> > the lock chain.
>
> This should be fixed by the following commit when/if it's merged. The
> commit removes nci_mutex.
>
> nfc: Allow to create multiple virtual nci devices
> https://lore.kernel.org/all/20221104170422....@google.com/

#syz fix: NFC: nci: Allow to create multiple virtual nci devices
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