[syzbot] INFO: trying to register non-static key in __access_remote_vm

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8755ae45a9e8 Add linux-next specific files for 20220819
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1420bffd080000
kernel config: https://syzkaller.appspot.com/x/.config?x=ead6107a3bbe3c62
dashboard link: https://syzkaller.appspot.com/bug?extid=d011b5a27f77c61c6345
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=170f3023080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e56b35080000

Bisection is inconclusive: the first bad commit could be any of:

4fae831b3a71 tty: n_gsm: fix packet re-transmission without open control channel
32dd59f96924 tty: n_gsm: fix race condition in gsmld_write()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=170af485080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d011b5...@syzkaller.appspotmail.com

INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 0 PID: 3617 Comm: syz-executor272 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1521
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 3617, name: syz-executor272
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
irq event stamp: 4716
hardirqs last enabled at (4715): [<ffffffff898354ff>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last enabled at (4715): [<ffffffff898354ff>] _raw_spin_unlock_irq+0x1f/0x40 kernel/locking/spinlock.c:202
hardirqs last disabled at (4716): [<ffffffff8983532e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (4716): [<ffffffff8983532e>] _raw_spin_lock_irqsave+0x4e/0x50 kernel/locking/spinlock.c:162
softirqs last enabled at (4594): [<ffffffff81491a33>] invoke_softirq kernel/softirq.c:445 [inline]
softirqs last enabled at (4594): [<ffffffff81491a33>] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
softirqs last disabled at (4561): [<ffffffff81491a33>] invoke_softirq kernel/softirq.c:445 [inline]
softirqs last disabled at (4561): [<ffffffff81491a33>] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 0 PID: 3617 Comm: syz-executor272 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0
syz-executor272[3617] cmdline: ./syz-executor2726460068
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:122 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:140
__might_resched.cold+0x222/0x26b kernel/sched/core.c:9896
down_read_killable+0x75/0x490 kernel/locking/rwsem.c:1521
mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline]
__access_remote_vm+0xac/0x6f0 mm/memory.c:5461
get_mm_cmdline.part.0+0x217/0x620 fs/proc/base.c:299
get_mm_cmdline fs/proc/base.c:367 [inline]
get_task_cmdline_kernel+0x1d9/0x220 fs/proc/base.c:367
dump_stack_print_cmdline.part.0+0x82/0x150 lib/dump_stack.c:61
dump_stack_print_cmdline lib/dump_stack.c:89 [inline]
dump_stack_print_info+0x185/0x190 lib/dump_stack.c:97
__dump_stack lib/dump_stack.c:121 [inline]
dump_stack_lvl+0xc1/0x134 lib/dump_stack.c:140
assign_lock_key kernel/locking/lockdep.c:979 [inline]
register_lock_class+0xf1b/0x1120 kernel/locking/lockdep.c:1292
__lock_acquire+0x109/0x56d0 kernel/locking/lockdep.c:4932
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
gsmld_write+0x5e/0x140 drivers/tty/n_gsm.c:3023
do_tty_write drivers/tty/tty_io.c:1024 [inline]
file_tty_write.constprop.0+0x499/0x8f0 drivers/tty/tty_io.c:1095
call_write_iter include/linux/fs.h:2188 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:578
ksys_write+0x127/0x250 fs/read_write.c:631
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: 0033:0x7fc136bf5289
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc832732f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc136bf5289
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fc136bb9070 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000000e R11: 0000000000000246 R12: 00007fc136bb9100
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
syz-executor272[3617] cmdline: ./syz-executor2726460068
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:122 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:140
assign_lock_key kernel/locking/lockdep.c:979 [inline]
register_lock_class+0xf1b/0x1120 kernel/locking/lockdep.c:1292
__lock_acquire+0x109/0x56d0 kernel/locking/lockdep.c:4932
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
gsmld_write+0x5e/0x140 drivers/tty/n_gsm.c:3023
do_tty_write drivers/tty/tty_io.c:1024 [inline]
file_tty_write.constprop.0+0x499/0x8f0 drivers/tty/tty_io.c:1095
call_write_iter include/linux/fs.h:2188 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:578
ksys_write+0x127/0x250 fs/read_write.c:631
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: 0033:0x7fc136bf5289
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP:


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Hillf Danton]

On Tue, 23 Aug 2022 18:45:31 -0700

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 8755ae45a9e8 Add linux-next specific files for 20220819
> git tree: linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1420bffd080000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ead6107a3bbe3c62
> dashboard link: https://syzkaller.appspot.com/bug?extid=d011b5a27f77c61c6345
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=170f3023080000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e56b35080000

Initialize lock earlier.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 8755ae45a9e8

--- x/drivers/tty/n_gsm.c
+++ n/drivers/tty/n_gsm.c
@@ -2608,6 +2608,8 @@ static struct gsm_mux *gsm_alloc_mux(voi
return NULL;
}
spin_lock_init(&gsm->lock);
+ spin_lock_init(&gsm->control_lock);
+ spin_lock_init(&gsm->tx_lock);
mutex_init(&gsm->mutex);
kref_init(&gsm->ref);
INIT_LIST_HEAD(&gsm->tx_ctrl_list);
--

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+d011b5...@syzkaller.appspotmail.com

Tested on:

commit: 8755ae45 Add linux-next specific files for 20220819
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1340610b080000

kernel config: https://syzkaller.appspot.com/x/.config?x=ead6107a3bbe3c62
dashboard link: https://syzkaller.appspot.com/bug?extid=d011b5a27f77c61c6345
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=1286ee0b080000

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

[Tetsuo Handa]

#syz dup: INFO: trying to register non-static key in gsmld_write