[syzbot] [serial?] general protection fault in serial8250_tx_chars

[syzbot <syzbot+837b8c9032c053262db8@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    6cd06ab12d1a gup: make the stack expansion warning a bit m..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13fdf29ca80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9b64180aaf312512
dashboard link: https://syzkaller.appspot.com/bug?extid=837b8c9032c053262db8
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b9ac6b68fe1/disk-6cd06ab1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/694d14350cd9/vmlinux-6cd06ab1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0344e65f0f1c/bzImage-6cd06ab1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+837b8c9032c053262db8@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 12722 Comm: kworker/1:25 Not tainted 6.4.0-syzkaller-11479-g6cd06ab12d1a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Workqueue: pm pm_runtime_work
RIP: 0010:serial8250_tx_chars+0x299/0x8b0 drivers/tty/serial/8250/8250_port.c:1813
Code: 5d 36 26 fd 48 8b 2b 48 8b 44 24 20 42 0f b6 04 38 84 c0 0f 85 8f 02 00 00 48 8b 04 24 48 63 00 48 01 c5 48 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 91 02 00 00 0f b6 6d 00 48 8b 44 24 60
RSP: 0018:ffffc9000abdf8d0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88801f1c0fd0 RCX: 1ffffffff246560f
RDX: 1ffffffff2465659 RSI: 0000000000000000 RDI: ffffffff9232b2d0
RBP: 0000000000000000 R08: ffffffff84be7c90 R09: fffff5200157bf14
R10: dffffc0000000000 R11: fffff5200157bf14 R12: 0000000000000010
R13: ffffffff9232b120 R14: ffffffff9232b020 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020404030 CR3: 000000000d130000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __start_tx+0x312/0x450 drivers/tty/serial/8250/8250_port.c:1547
 serial_port_runtime_resume+0x1ec/0x2a0 drivers/tty/serial/serial_port.c:40
 __rpm_callback+0x2b9/0x7a0 drivers/base/power/runtime.c:392
 rpm_callback drivers/base/power/runtime.c:446 [inline]
 rpm_resume+0x10b1/0x1af0 drivers/base/power/runtime.c:912
 pm_runtime_work+0x147/0x210 drivers/base/power/runtime.c:977
 process_one_work+0x92c/0x12c0 kernel/workqueue.c:2597
 worker_thread+0xa63/0x1210 kernel/workqueue.c:2748
 kthread+0x2b8/0x350 kernel/kthread.c:389
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:serial8250_tx_chars+0x299/0x8b0 drivers/tty/serial/8250/8250_port.c:1813
Code: 5d 36 26 fd 48 8b 2b 48 8b 44 24 20 42 0f b6 04 38 84 c0 0f 85 8f 02 00 00 48 8b 04 24 48 63 00 48 01 c5 48 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 91 02 00 00 0f b6 6d 00 48 8b 44 24 60
RSP: 0018:ffffc9000abdf8d0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88801f1c0fd0 RCX: 1ffffffff246560f
RDX: 1ffffffff2465659 RSI: 0000000000000000 RDI: ffffffff9232b2d0
RBP: 0000000000000000 R08: ffffffff84be7c90 R09: fffff5200157bf14
R10: dffffc0000000000 R11: fffff5200157bf14 R12: 0000000000000010
R13: ffffffff9232b120 R14: ffffffff9232b020 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020404030 CR3: 000000000d130000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	5d                   	pop    %rbp
   1:	36 26 fd             	ss es std
   4:	48 8b 2b             	mov    (%rbx),%rbp
   7:	48 8b 44 24 20       	mov    0x20(%rsp),%rax
   c:	42 0f b6 04 38       	movzbl (%rax,%r15,1),%eax
  11:	84 c0                	test   %al,%al
  13:	0f 85 8f 02 00 00    	jne    0x2a8
  19:	48 8b 04 24          	mov    (%rsp),%rax
  1d:	48 63 00             	movslq (%rax),%rax
  20:	48 01 c5             	add    %rax,%rbp
  23:	48 89 e8             	mov    %rbp,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 38       	movzbl (%rax,%r15,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 91 02 00 00    	jne    0x2c8
  37:	0f b6 6d 00          	movzbl 0x0(%rbp),%ebp
  3b:	48 8b 44 24 60       	mov    0x60(%rsp),%rax


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