[syzbot] [usb?] possible deadlock in chaoskey_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a9fe2a8ac53 dt-bindings: usb: dwc3-imx8mp: add compatible..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=14b53bd0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4510af5d637450fb
dashboard link: https://syzkaller.appspot.com/bug?extid=685e14d04fe35692d3bc
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1029d380580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=158cd307980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/883c5319cb52/disk-4a9fe2a8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/caf4421ed2ef/vmlinux-4a9fe2a8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d8e3beb01d49/bzImage-4a9fe2a8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+685e14...@syzkaller.appspotmail.com

raw-gadget.0 gadget.0: fail, usb_ep_enable returned -22
============================================
WARNING: possible recursive locking detected
6.12.0-rc1-syzkaller-00027-g4a9fe2a8ac53 #0 Not tainted
--------------------------------------------
syz-executor363/2651 is trying to acquire lock:
ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_release+0x15d/0x2c0 drivers/usb/misc/chaoskey.c:322

but task is already holding lock:
ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_release+0x7f/0x2c0 drivers/usb/misc/chaoskey.c:299

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(chaoskey_list_lock);
lock(chaoskey_list_lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

1 lock held by syz-executor363/2651:
#0: ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_release+0x7f/0x2c0 drivers/usb/misc/chaoskey.c:299

stack backtrace:
CPU: 0 UID: 0 PID: 2651 Comm: syz-executor363 Not tainted 6.12.0-rc1-syzkaller-00027-g4a9fe2a8ac53 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_deadlock_bug+0x2e3/0x410 kernel/locking/lockdep.c:3037
check_deadlock kernel/locking/lockdep.c:3089 [inline]
validate_chain kernel/locking/lockdep.c:3891 [inline]
__lock_acquire+0x2185/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
chaoskey_release+0x15d/0x2c0 drivers/usb/misc/chaoskey.c:322
__fput+0x3f6/0xb60 fs/file_table.c:431
task_work_run+0x14e/0x250 kernel/task_work.c:228
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0xadd/0x2ce0 kernel/exit.c:939
do_group_exit+0xd3/0x2a0 kernel/exit.c:1088
__do_sys_exit_group kernel/exit.c:1099 [inline]
__se_sys_exit_group kernel/exit.c:1097 [inline]
__x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1097
x64_sys_call+0x14a9/0x16a0 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd87e4bb409
Code: Unable to access opcode bytes at 0x7fd87e4bb3df.
RSP: 002b:00007ffcb70ccdd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd87e4bb409
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fd87e536370 R08: ffffffffffffffb8 R09: 00007ffcb70ccb47
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd87e536370
R13: 0000000000000000 R14: 00007fd87e53a080 R15: 00007fd87e489670
</TASK>


---
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See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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#syz test: git://repo/address.git branch-or-commit-hash
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#syz undup

[Edward Adam Davis]

delay get the chaoskey_list_lock, avoid to circular locking dependency
chaoskey_release has a wrong logic lock for chaoskey_list_lock, it need unlock.

#syz test

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index e8b63df5f975..225863321dc4 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -232,10 +232,10 @@ static void chaoskey_disconnect(struct usb_interface *interface)
if (dev->hwrng_registered)
hwrng_unregister(&dev->hwrng);

- mutex_lock(&chaoskey_list_lock);
usb_deregister_dev(interface, &chaoskey_class);

usb_set_intfdata(interface, NULL);
+ mutex_lock(&chaoskey_list_lock);
mutex_lock(&dev->lock);

dev->present = false;
@@ -319,7 +319,7 @@ static int chaoskey_release(struct inode *inode, struct file *file)
bail:
mutex_unlock(&dev->lock);
destruction:
- mutex_lock(&chaoskey_list_lock);
+ mutex_unlock(&chaoskey_list_lock);
usb_dbg(interface, "release success");
return rv;
}

[syzbot]

Hello,

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

Reported-by: syzbot+685e14...@syzkaller.appspotmail.com
Tested-by: syzbot+685e14...@syzkaller.appspotmail.com

Tested on:

commit: 4a9fe2a8 dt-bindings: usb: dwc3-imx8mp: add compatible..

git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing

console output: https://syzkaller.appspot.com/x/log.txt?x=115fbf9f980000

kernel config: https://syzkaller.appspot.com/x/.config?x=4510af5d637450fb
dashboard link: https://syzkaller.appspot.com/bug?extid=685e14d04fe35692d3bc
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=105e1327980000

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

[Edward Adam Davis]

[Syzbot reported two possible deadlocks]
The first possible deadlock is:

WARNING: possible recursive locking detected
6.12.0-rc1-syzkaller-00027-g4a9fe2a8ac53 #0 Not tainted
--------------------------------------------
syz-executor363/2651 is trying to acquire lock:
ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_release+0x15d/0x2c0 drivers/usb/misc/chaoskey.c:322

but task is already holding lock:
ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_release+0x7f/0x2c0 drivers/usb/misc/chaoskey.c:299

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(chaoskey_list_lock);
lock(chaoskey_list_lock);

*** DEADLOCK ***

The second possible deadlock is:
WARNING: possible circular locking dependency detected
6.12.0-rc1-syzkaller-00027-g4a9fe2a8ac53 #0 Not tainted
------------------------------------------------------
kworker/0:2/804 is trying to acquire lock:
ffffffff899dadb0 (minor_rwsem){++++}-{3:3}, at: usb_deregister_dev+0x7c/0x1e0 drivers/usb/core/file.c:186

but task is already holding lock:

ffffffff89b120e8 (chaoskey_list_lock){+.+.}-{3:3}, at: chaoskey_disconnect+0xa8/0x2a0 drivers/usb/misc/chaoskey.c:235

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (chaoskey_list_lock){+.+.}-{3:3}:

__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752

chaoskey_open+0xdd/0x220 drivers/usb/misc/chaoskey.c:274
usb_open+0x186/0x220 drivers/usb/core/file.c:47
chrdev_open+0x237/0x6a0 fs/char_dev.c:414
do_dentry_open+0x6cb/0x1390 fs/open.c:958
vfs_open+0x82/0x3f0 fs/open.c:1088
do_open fs/namei.c:3774 [inline]
path_openat+0x1e6a/0x2d60 fs/namei.c:3933
do_filp_open+0x1dc/0x430 fs/namei.c:3960
do_sys_openat2+0x17a/0x1e0 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_openat fs/open.c:1446 [inline]
__se_sys_openat fs/open.c:1441 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1441

do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (minor_rwsem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
down_write+0x93/0x200 kernel/locking/rwsem.c:1577
usb_deregister_dev+0x7c/0x1e0 drivers/usb/core/file.c:186
chaoskey_disconnect+0xb7/0x2a0 drivers/usb/misc/chaoskey.c:236
usb_unbind_interface+0x1e8/0x970 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:569 [inline]
device_remove+0x122/0x170 drivers/base/dd.c:561
__device_release_driver drivers/base/dd.c:1273 [inline]
device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1296
bus_remove_device+0x22f/0x420 drivers/base/bus.c:576
device_del+0x396/0x9f0 drivers/base/core.c:3864
usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1418
usb_disconnect+0x2e1/0x920 drivers/usb/core/hub.c:2304
hub_port_connect drivers/usb/core/hub.c:5361 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5661 [inline]
port_event drivers/usb/core/hub.c:5821 [inline]
hub_event+0x1bed/0x4f40 drivers/usb/core/hub.c:5903
process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(chaoskey_list_lock);
lock(minor_rwsem);
lock(chaoskey_list_lock);
lock(minor_rwsem);

*** DEADLOCK ***
[Analysis]
The first is AA lock, it because wrong logic, it need a unlock.
The second is AB lock, it needs to rearrange the order of lock usage.

Fixes: 422dc0a4d12d ("USB: chaoskey: fail open after removal")
Reported-by: syzbot+685e14...@syzkaller.appspotmail.com
Reported-by: syzbot+1f8ca5...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=685e14d04fe35692d3bc
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
drivers/usb/misc/chaoskey.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index e8b63df5f975..225863321dc4 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -232,10 +232,10 @@ static void chaoskey_disconnect(struct usb_interface *interface)
if (dev->hwrng_registered)
hwrng_unregister(&dev->hwrng);

- mutex_lock(&chaoskey_list_lock);
usb_deregister_dev(interface, &chaoskey_class);

usb_set_intfdata(interface, NULL);
+ mutex_lock(&chaoskey_list_lock);
mutex_lock(&dev->lock);

dev->present = false;
@@ -319,7 +319,7 @@ static int chaoskey_release(struct inode *inode, struct file *file)
bail:
mutex_unlock(&dev->lock);
destruction:
- mutex_lock(&chaoskey_list_lock);
+ mutex_unlock(&chaoskey_list_lock);
usb_dbg(interface, "release success");
return rv;
}

--
2.43.0