BUG: sleeping function called from invalid context in __might_resched

[Yu Hao]

Hello,

We found the following issue using syzkaller on Linux v6.2.0.
A similar bug was found in function `n_hdlc_tty_wakeup` before.
(https://groups.google.com/g/syzkaller-bugs/c/XAyZCUO-eAY/m/Lpj5SzDNAwAJ)
Now it is found in a different caller `gsmld_write`.
It needs to fix the bug in `gsmld_write` again.

The full report including the C reproducer:
https://gist.github.com/ZHYfeng/eb410de5d7aec253d8c83cf34e628d6a

The brief report is below:

Syzkaller hit 'BUG: sleeping function called from invalid context in
__might_resched' bug.

BUG: sleeping function called from invalid context at
kernel/printk/printk.c:2656
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 9817, name: (agetty)
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
3 locks held by (agetty)/9817:
 #0: ffff888017797098 (&tty->ldisc_sem){++++}-{0:0}, at:
tty_ldisc_ref_wait+0x27/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffff888017797130 (&tty->atomic_write_lock){+.+.}-{3:3}, at:
tty_write_lock+0x23/0x90 drivers/tty/tty_io.c:944
 #2: ffff888046ee93e0 (&gsm->tx_lock){....}-{2:2}, at:
gsmld_write+0x63/0x150 drivers/tty/n_gsm.c:3410
irq event stamp: 3146
hardirqs last  enabled at (3145): [<ffffffff8a0f3a32>]
syscall_enter_from_user_mode+0x22/0xb0 kernel/entry/common.c:111
hardirqs last disabled at (3146): [<ffffffff8a12e6b3>]
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (3146): [<ffffffff8a12e6b3>]
_raw_spin_lock_irqsave+0x53/0x60 kernel/locking/spinlock.c:162
softirqs last  enabled at (0): [<ffffffff814b301d>]
copy_process+0x1a8d/0x7490 kernel/fork.c:2211
softirqs last disabled at (0): [<0000000000000000>] 0x0
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 0 PID: 9817 Comm: (agetty) Not tainted 6.2.0 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 __might_resched.cold+0x222/0x26b kernel/sched/core.c:10045
 console_lock+0x1c/0x80 kernel/printk/printk.c:2656
 do_con_write+0x114/0x1e40 drivers/tty/vt/vt.c:2908
 con_write+0x26/0x40 drivers/tty/vt/vt.c:3295
 gsmld_write+0xd0/0x150 drivers/tty/n_gsm.c:3413
 do_tty_write drivers/tty/tty_io.c:1018 [inline]
 file_tty_write.isra.0+0x48f/0x820 drivers/tty/tty_io.c:1089
 call_write_iter include/linux/fs.h:2189 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x9cf/0xd90 fs/read_write.c:584
 ksys_write+0x12c/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f5538c101b0
Code: 2e 0f 1f 84 00 00 00 00 00 90 48 8b 05 19 7e 20 00 c3 0f 1f 84
00 00 00 00 00 83 3d 19 c2 20 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ae fc ff ff 48 89 04 24
RSP: 002b:00007ffdb4aadbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 00007f5538c101b0
RDX: 000000000000000a RSI: 00007f553b13ccbe RDI: 0000000000000003
RBP: 00007f553b13ccbe R08: 00007ffdb4aadba0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: ffffffffffffffff R15: 00007ffdb4aadea0
 </TASK>