[syzbot] [input?] possible deadlock in evdev_cleanup (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fda5695d692c Merge branch 'for-next/core' 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=14de17c0980000
kernel config: https://syzkaller.appspot.com/x/.config?x=95dc1de8407c7270
dashboard link: https://syzkaller.appspot.com/bug?extid=77a2ec57108df22d5c63
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10298620980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=134d3182980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/07f3214ff0d9/disk-fda5695d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/70e2e2c864e8/vmlinux-fda5695d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b259942a16dc/Image-fda5695d.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+77a2ec...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller-gfda5695d692c #0 Not tainted
------------------------------------------------------
syz-executor144/6248 is trying to acquire lock:
ffff0000d6b65110 (&evdev->mutex){+.+.}-{3:3}, at: evdev_mark_dead drivers/input/evdev.c:1314 [inline]
ffff0000d6b65110 (&evdev->mutex){+.+.}-{3:3}, at: evdev_cleanup+0x38/0x16c drivers/input/evdev.c:1323

but task is already holding lock:
ffff800090ffb888 (input_mutex){+.+.}-{3:3}, at: __input_unregister_device+0x2a4/0x5c0 drivers/input/input.c:2219

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (input_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
__mutex_lock kernel/locking/mutex.c:752 [inline]
mutex_lock_interruptible_nested+0x2c/0x38 kernel/locking/mutex.c:826
input_register_device+0x8dc/0xde8 drivers/input/input.c:2389
uinput_create_device+0x360/0x528 drivers/input/misc/uinput.c:365
uinput_ioctl_handler+0x8b0/0x16c0 drivers/input/misc/uinput.c:904
uinput_ioctl+0x38/0x4c drivers/input/misc/uinput.c:1075
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl fs/ioctl.c:890 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:890
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #2 (&newdev->mutex){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
__mutex_lock kernel/locking/mutex.c:752 [inline]
mutex_lock_interruptible_nested+0x2c/0x38 kernel/locking/mutex.c:826
uinput_request_send drivers/input/misc/uinput.c:151 [inline]
uinput_request_submit+0x188/0x654 drivers/input/misc/uinput.c:182
uinput_dev_upload_effect+0x170/0x218 drivers/input/misc/uinput.c:257
input_ff_upload+0x49c/0x834 drivers/input/ff-core.c:150
evdev_do_ioctl drivers/input/evdev.c:1183 [inline]
evdev_ioctl_handler+0x1fd0/0x2d58 drivers/input/evdev.c:1272
evdev_ioctl+0x38/0x4c drivers/input/evdev.c:1281
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl fs/ioctl.c:890 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:890
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #1 (&ff->mutex){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
__mutex_lock kernel/locking/mutex.c:752 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
input_ff_upload+0x31c/0x834 drivers/input/ff-core.c:120
evdev_do_ioctl drivers/input/evdev.c:1183 [inline]
evdev_ioctl_handler+0x1fd0/0x2d58 drivers/input/evdev.c:1272
evdev_ioctl+0x38/0x4c drivers/input/evdev.c:1281
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:904 [inline]
__se_sys_ioctl fs/ioctl.c:890 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:890
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #0 (&evdev->mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
lock_acquire+0x248/0x73c kernel/locking/lockdep.c:5754
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
__mutex_lock kernel/locking/mutex.c:752 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
evdev_mark_dead drivers/input/evdev.c:1314 [inline]
evdev_cleanup+0x38/0x16c drivers/input/evdev.c:1323
evdev_disconnect+0x58/0xc0 drivers/input/evdev.c:1407
__input_unregister_device+0x31c/0x5c0 drivers/input/input.c:2222
input_unregister_device+0xb0/0xfc drivers/input/input.c:2440
uinput_destroy_device+0x5a4/0x79c drivers/input/misc/uinput.c:299
uinput_release+0x44/0x60 drivers/input/misc/uinput.c:744
__fput+0x30c/0x738 fs/file_table.c:422
____fput+0x20/0x30 fs/file_table.c:450
task_work_run+0x230/0x2e0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x4e4/0x1ac8 kernel/exit.c:878
do_group_exit+0x194/0x22c kernel/exit.c:1027
__do_sys_exit_group kernel/exit.c:1038 [inline]
__se_sys_exit_group kernel/exit.c:1036 [inline]
pid_child_should_wake+0x0/0x1dc kernel/exit.c:1036
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

other info that might help us debug this:

Chain exists of:
&evdev->mutex --> &newdev->mutex --> input_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(input_mutex);
lock(&newdev->mutex);
lock(input_mutex);
lock(&evdev->mutex);

*** DEADLOCK ***

1 lock held by syz-executor144/6248:
#0: ffff800090ffb888 (input_mutex){+.+.}-{3:3}, at: __input_unregister_device+0x2a4/0x5c0 drivers/input/input.c:2219

stack backtrace:
CPU: 0 PID: 6248 Comm: syz-executor144 Not tainted 6.9.0-rc7-syzkaller-gfda5695d692c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114
dump_stack+0x1c/0x28 lib/dump_stack.c:123
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
lock_acquire+0x248/0x73c kernel/locking/lockdep.c:5754
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
__mutex_lock kernel/locking/mutex.c:752 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
evdev_mark_dead drivers/input/evdev.c:1314 [inline]
evdev_cleanup+0x38/0x16c drivers/input/evdev.c:1323
evdev_disconnect+0x58/0xc0 drivers/input/evdev.c:1407
__input_unregister_device+0x31c/0x5c0 drivers/input/input.c:2222
input_unregister_device+0xb0/0xfc drivers/input/input.c:2440
uinput_destroy_device+0x5a4/0x79c drivers/input/misc/uinput.c:299
uinput_release+0x44/0x60 drivers/input/misc/uinput.c:744
__fput+0x30c/0x738 fs/file_table.c:422
____fput+0x20/0x30 fs/file_table.c:450
task_work_run+0x230/0x2e0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x4e4/0x1ac8 kernel/exit.c:878
do_group_exit+0x194/0x22c kernel/exit.c:1027
__do_sys_exit_group kernel/exit.c:1038 [inline]
__se_sys_exit_group kernel/exit.c:1036 [inline]
pid_child_should_wake+0x0/0x1dc kernel/exit.c:1036
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598


---
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[Hillf Danton]

On Sat, 18 May 2024 07:18:36 -0700

> syzbot found the following issue on:
>
> HEAD commit: fda5695d692c Merge branch 'for-next/core' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=134d3182980000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

--- l/drivers/input/misc/uinput.c
+++ u/drivers/input/misc/uinput.c
@@ -311,6 +311,7 @@ static int uinput_create_device(struct u
struct input_dev *dev = udev->dev;
int error, nslot;

+ lockdep_assert_held(&udev->mutex);
if (udev->state != UIST_SETUP_COMPLETE) {
printk(KERN_DEBUG "%s: write device info first\n", UINPUT_NAME);
return -EINVAL;
@@ -362,7 +363,9 @@ static int uinput_create_device(struct u

input_set_drvdata(udev->dev, udev);

- error = input_register_device(udev->dev);
+ mutex_unlock(&udev->mutex);
+ error = input_register_device(dev);
+ mutex_lock(&udev->mutex);
if (error)
goto fail2;

--

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+77a2ec...@syzkaller.appspotmail.com

Tested on:

commit: fda5695d Merge branch 'for-next/core' into for-kernelci
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1507e5dc980000

kernel config: https://syzkaller.appspot.com/x/.config?x=95dc1de8407c7270
dashboard link: https://syzkaller.appspot.com/bug?extid=77a2ec57108df22d5c63
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=14a15634980000

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