Re: [syzbot] [usb?] possible deadlock in assign_fw

[syzbot <syzbot+e70e4c6f6eee43357ba7@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    d5d547aa7b51 Merge tag 'random-6.11-rc6-for-linus' of git:..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1493808f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d76559f775f44ba6
dashboard link: https://syzkaller.appspot.com/bug?extid=e70e4c6f6eee43357ba7
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=14ee2b7b980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=177c7b7b980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/28e0e4e1eeef/disk-d5d547aa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/72b0f7665fc8/vmlinux-d5d547aa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/96e3870a77f6/bzImage-d5d547aa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e70e4c6f6eee43357ba7@syzkaller.appspotmail.com

R13: 0000000000000001 R14: 00746f687370616e R15: 616e732f7665642f
 </TASK>
============================================
WARNING: possible recursive locking detected
6.11.0-rc5-syzkaller-00081-gd5d547aa7b51 #0 Not tainted
--------------------------------------------
syz-executor300/5260 is trying to acquire lock:
ffffffff8f293008 (fw_lock){+.+.}-{3:3}, at: assign_fw+0x56/0x890 drivers/base/firmware_loader/main.c:700

but task is already holding lock:
ffffffff8f293008 (fw_lock){+.+.}-{3:3}, at: device_cache_fw_images drivers/base/firmware_loader/main.c:1519 [inline]
ffffffff8f293008 (fw_lock){+.+.}-{3:3}, at: fw_pm_notify+0x232/0x2f0 drivers/base/firmware_loader/main.c:1572

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

       CPU0
       ----
  lock(fw_lock);
  lock(fw_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz-executor300/5260:
 #0: ffffffff8f145568 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x5c/0x390 drivers/char/misc.c:129
 #1: ffffffff8e7eb608 (system_transition_mutex){+.+.}-{3:3}, at: lock_system_sleep+0x60/0xa0 kernel/power/main.c:56
 #2: ffffffff8e80bab0 ((pm_chain_head).rwsem){++++}-{3:3}, at: blocking_notifier_call_chain_robust+0xac/0x1e0 kernel/notifier.c:352
 #3: ffffffff8f293008 (fw_lock){+.+.}-{3:3}, at: device_cache_fw_images drivers/base/firmware_loader/main.c:1519 [inline]
 #3: ffffffff8f293008 (fw_lock){+.+.}-{3:3}, at: fw_pm_notify+0x232/0x2f0 drivers/base/firmware_loader/main.c:1572
 #4: ffffffff8f28e0a8 (dpm_list_mtx){+.+.}-{3:3}, at: device_pm_lock drivers/base/power/main.c:113 [inline]
 #4: ffffffff8f28e0a8 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_for_each_dev+0x2b/0xc0 drivers/base/power/main.c:1961

stack backtrace:
CPU: 0 UID: 0 PID: 5260 Comm: syz-executor300 Not tainted 6.11.0-rc5-syzkaller-00081-gd5d547aa7b51 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 check_deadlock kernel/locking/lockdep.c:3061 [inline]
 validate_chain+0x15d3/0x5900 kernel/locking/lockdep.c:3855
 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 assign_fw+0x56/0x890 drivers/base/firmware_loader/main.c:700
 _request_firmware+0xd0a/0x12b0 drivers/base/firmware_loader/main.c:917
 request_firmware drivers/base/firmware_loader/main.c:963 [inline]
 cache_firmware drivers/base/firmware_loader/main.c:1301 [inline]
 __async_dev_cache_fw_image+0xe7/0x320 drivers/base/firmware_loader/main.c:1415
 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:1471
 dpm_for_each_dev+0x58/0xc0 drivers/base/power/main.c:1963
 device_cache_fw_images drivers/base/firmware_loader/main.c:1521 [inline]
 fw_pm_notify+0x24a/0x2f0 drivers/base/firmware_loader/main.c:1572
 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+0x138/0x280 kernel/power/user.c:87
 misc_open+0x313/0x390 drivers/char/misc.c:165
 chrdev_open+0x5b0/0x630 fs/char_dev.c:414
 do_dentry_open+0x970/0x1440 fs/open.c:959
 vfs_open+0x3e/0x330 fs/open.c:1089
 do_open fs/namei.c:3727 [inline]
 path_openat+0x2b3e/0x3470 fs/namei.c:3886
 do_filp_open+0x235/0x490 fs/namei.c:3913
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1416
 do_sys_open fs/open.c:1431 [inline]
 __do_sys_openat fs/open.c:1447 [inline]
 __se_sys_openat fs/open.c:1442 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1442
 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: 0033:0x7fec1643df29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 1e 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:00007fec163e9208 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fec164c4188 RCX: 00007fec1643df29
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: ffffffffffffff9c
RBP: 00007fec164c4180 R08: 00007fec163e8fa7 R09: 0000000000000038
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fec163e9210
R13: 0000000000000001 R14: 00746f687370616e R15: 616e732f7665642f
 </TASK>


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