[syzbot] [pm?] [usb?] possible deadlock in dpm_for_each_dev

From: syzbot
Date: Sun Jul 07 2024 - 13:25:31 EST

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Hello,

syzbot found the following issue on:

HEAD commit: e9d22f7a6655 Merge tag 'linux_kselftest-fixes-6.10-rc7' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13fff269980000
kernel config: https://syzkaller.appspot.com/x/.config?x=864caee5f78cab51
dashboard link: https://syzkaller.appspot.com/bug?extid=2a03726f1d4eff48b278
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17013a35980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16d7af25980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3dd72a93425/disk-e9d22f7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9d79986da9dc/vmlinux-e9d22f7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0df271bec574/bzImage-e9d22f7a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2a03726f1d4eff48b278@xxxxxxxxxxxxxxxxxxxxxxxxx

R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb90b6ce6c0
R13: 00007fb90b60f210 R14: 0000000000000001 R15: 616e732f7665642f
</TASK>
(NULL device *): loading /lib/firmware/dvb-usb-dib0700-1.20.fw failed with error -12
(NULL device *): Direct firmware load for dvb-usb-dib0700-1.20.fw failed with error -12
(NULL device *): Falling back to sysfs fallback for: dvb-usb-dib0700-1.20.fw
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc6-syzkaller-00061-ge9d22f7a6655 #0 Not tainted
------------------------------------------------------
syz-executor143/5112 is trying to acquire lock:
ffffffff8e1dd7b0 (umhelper_sem){++++}-{3:3}, at: usermodehelper_read_trylock+0x140/0x300 kernel/umh.c:215

but task is already holding lock:
ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: device_pm_lock drivers/base/power/main.c:113 [inline]
ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_for_each_dev+0x2b/0xc0 drivers/base/power/main.c:1961

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (dpm_list_mtx){+.+.}-{3:3}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
device_pm_add+0x78/0x320 drivers/base/power/main.c:137
device_add+0x5e8/0xbf0 drivers/base/core.c:3642
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:86 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:162 [inline]
firmware_fallback_sysfs+0x307/0x9e0 drivers/base/firmware_loader/fallback.c:238
_request_firmware+0xcf5/0x12b0 drivers/base/firmware_loader/main.c:914
request_firmware_work_func+0x12a/0x280 drivers/base/firmware_loader/main.c:1165
process_one_work kernel/workqueue.c:3248 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3329
worker_thread+0x86d/0xd50 kernel/workqueue.c:3409
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (umhelper_sem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526
usermodehelper_read_trylock+0x140/0x300 kernel/umh.c:215
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:147 [inline]
firmware_fallback_sysfs+0x184/0x9e0 drivers/base/firmware_loader/fallback.c:238
_request_firmware+0xcf5/0x12b0 drivers/base/firmware_loader/main.c:914
request_firmware drivers/base/firmware_loader/main.c:963 [inline]
cache_firmware drivers/base/firmware_loader/main.c:1265 [inline]
__async_dev_cache_fw_image+0xe7/0x320 drivers/base/firmware_loader/main.c:1379
async_schedule_node_domain+0xdc/0x110 kernel/async.c:221
async_schedule_domain include/linux/async.h:72 [inline]
dev_cache_fw_image+0x36d/0x3e0 drivers/base/firmware_loader/main.c:1435
dpm_for_each_dev+0x58/0xc0 drivers/base/power/main.c:1963
device_cache_fw_images drivers/base/firmware_loader/main.c:1485 [inline]
fw_pm_notify+0x24a/0x2f0 drivers/base/firmware_loader/main.c:1536
notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
notifier_call_chain_robust kernel/notifier.c:128 [inline]
blocking_notifier_call_chain_robust+0xe8/0x1e0 kernel/notifier.c:353
pm_notifier_call_chain_robust+0x2c/0x60 kernel/power/main.c:102
snapshot_open+0x1a1/0x280 kernel/power/user.c:77
misc_open+0x313/0x390 drivers/char/misc.c:165
chrdev_open+0x5b0/0x630 fs/char_dev.c:414
do_dentry_open+0x970/0x1450 fs/open.c:955
vfs_open+0x3e/0x330 fs/open.c:1086
do_open fs/namei.c:3654 [inline]
path_openat+0x2c01/0x35f0 fs/namei.c:3813
do_filp_open+0x235/0x490 fs/namei.c:3840
do_sys_openat2+0x13e/0x1d0 fs/open.c:1413
do_sys_open fs/open.c:1428 [inline]
__do_sys_openat fs/open.c:1444 [inline]
__se_sys_openat fs/open.c:1439 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1439
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(dpm_list_mtx);
lock(umhelper_sem);
lock(dpm_list_mtx);
rlock(umhelper_sem);

*** DEADLOCK ***

5 locks held by syz-executor143/5112:
#0: ffffffff8eb2f6e8 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x5c/0x390 drivers/char/misc.c:129
#1: ffffffff8e1e7368 (system_transition_mutex){+.+.}-{3:3}, at: lock_system_sleep+0x60/0xa0 kernel/power/main.c:56
#2: ffffffff8e2077f0 ((pm_chain_head).rwsem){++++}-{3:3}, at: blocking_notifier_call_chain_robust+0xac/0x1e0 kernel/notifier.c:352
#3: ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: device_cache_fw_images drivers/base/firmware_loader/main.c:1483 [inline]
#3: ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: fw_pm_notify+0x232/0x2f0 drivers/base/firmware_loader/main.c:1536
#4: ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: device_pm_lock drivers/base/power/main.c:113 [inline]
#4: ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_for_each_dev+0x2b/0xc0 drivers/base/power/main.c:1961

stack backtrace:
CPU: 0 PID: 5112 Comm: syz-executor143 Not tainted 6.10.0-rc6-syzkaller-00061-ge9d22f7a6655 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
check_noncircular+0x36a/0x4a0 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+0x18e0/0x5900 kernel/locking/lockdep.c:3869
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526
usermodehelper_read_trylock+0x140/0x300 kernel/umh.c:215
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:147 [inline]
firmware_fallback_sysfs+0x184/0x9e0 drivers/base/firmware_loader/fallback.c:238
_request_firmware+0xcf5/0x12b0 drivers/base/firmware_loader/main.c:914
request_firmware drivers/base/firmware_loader/main.c:963 [inline]
cache_firmware drivers/base/firmware_loader/main.c:1265 [inline]
__async_dev_cache_fw_image+0xe7/0x320 drivers/base/firmware_loader/main.c:1379
async_schedule_node_domain+0xdc/0x110 kernel/async.c:221
async_schedule_domain include/linux/async.h:72 [inline]
dev_cache_fw_image+0x36d/0x3e0 drivers/base/firmware_loader/main.c:1435
dpm_for_each_dev+0x58/0xc0 drivers/base/power/main.c:1963
device_cache_fw_images drivers/base/firmware_loader/main.c:1485 [inline]
fw_pm_notify+0x24a/0x2f0 drivers/base/firmware_loader/main.c:1536
notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
notifier_call_chain_robust kernel/notifier.c:128 [inline]
blocking_notifier_call_chain_robust+0xe8/0x1e0 kernel/notifier.c:353
pm_notifier_call_chain_robust+0x2c/0x60 kernel/power/main.c:102
snapshot_open+0x1a1/0x280 kernel/power/user.c:77
misc_open+0x313/0x390 drivers/char/misc.c:165
chrdev_open+0x5b0/0x630 fs/char_dev.c:414
do_dentry_open+0x970/0x1450 fs/open.c:955
vfs_open+0x3e/0x330 fs/open.c:1086
do_open fs/namei.c:3654 [inline]
path_openat+0x2c01/0x35f0 fs/namei.c:3813
do_filp_open+0x235/0x490 fs/namei.c:3840
do_sys_openat2+0x13e/0x1d0 fs/open.c:1413
do_sys_open fs/open.c:1428 [inline]
__do_sys_openat fs/open.c:1444 [inline]
__se_sys_openat fs/open.c:1439 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1439
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb90b681389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 1b 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb90b60f208 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb90b7013f8 RCX: 00007fb90b681389
RDX: 0000000000000000 RSI: 0000000020000080 RDI: ffffffffffffff9c
RBP: 00007fb90b7013f0 R08: 00007fb90b60efa7 R09: 0000000000000038
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb90b6ce6c0
R13: 00007fb90b60f210 R14: 0000000000000001 R15: 616e732f7665642f
</TASK>

---
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