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BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out

Status: closed as dup on 2019/12/13 09:05
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+92f32d4e21fb246d31a2@syzkaller.appspotmail.com
First crash: 1810d, last: 1800d
Cause bisection: introduced by (bisect log) :
commit bd94c4077a0b2ecc35562c294f80f3659ecd8499
Author: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Wed Oct 28 03:46:05 2015 +0000

  serial: support 16-bit register interface for console

Crash: BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out (log)
Repro: C syz .config
  
▶ ▼ Duplicate of
Title Repro Cause bisect Fix bisect Count Last Reported
BUG: unable to handle kernel NULL pointer dereference in mem_serial_out serial C done 7 1800d 1813d
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] serial: 8250: fix NULL pointer dereference in serial8250_do_startup() 4 (5) 2021/05/13 14:24
BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out 2 (4) 2019/12/13 09:05
▶ ▼ Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out C inconclusive 2 1620d 1811d 0/1 upstream: reported C repro on 2019/12/08 23:15
linux-4.19 BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out C error 2 1529d 1811d 0/1 upstream: reported C repro on 2019/12/08 23:44

Sample crash report:
BUG: kernel NULL pointer dereference, address: 0000000000000002
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 99645067 P4D 99645067 PUD 927c5067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9374 Comm: syz-executor246 Not tainted 5.5.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:writew arch/x86/include/asm/io.h:66 [inline]
RIP: 0010:mem16_serial_out+0x6c/0x90 drivers/tty/serial/8250/8250_port.c:414
Code: b6 8d e9 00 00 00 49 8d 7d 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 19 48 63 db 49 03 5d 40 <66> 44 89 23 5b 41 5c 41 5d 5d c3 e8 d4 2d cf fd eb c2 e8 2d 2e cf
RSP: 0018:ffffc90001fa78e8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 1ffffffff182040e RSI: ffffffff83e397f6 RDI: ffffffff8c102070
RBP: ffffc90001fa7900 R08: ffff888095842080 R09: ffffed10144ce1c6
R10: ffffed10144ce1c5 R11: ffff8880a2670e2b R12: 0000000000000001
R13: ffffffff8c102030 R14: ffffc90001fa7a40 R15: ffffffff8c102188
FS:  000000000177c880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 00000000a6ab1000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 serial_out drivers/tty/serial/8250/8250.h:118 [inline]
 serial8250_clear_fifos.part.0+0x3a/0xb0 drivers/tty/serial/8250/8250_port.c:557
 serial8250_clear_fifos drivers/tty/serial/8250/8250_port.c:556 [inline]
 serial8250_do_startup+0x426/0x1cf0 drivers/tty/serial/8250/8250_port.c:2121
 serial8250_startup+0x62/0x80 drivers/tty/serial/8250/8250_port.c:2329
 uart_port_startup drivers/tty/serial/serial_core.c:219 [inline]
 uart_startup drivers/tty/serial/serial_core.c:258 [inline]
 uart_startup+0x452/0x980 drivers/tty/serial/serial_core.c:249
 uart_set_info drivers/tty/serial/serial_core.c:998 [inline]
 uart_set_info_user+0x13b4/0x1cf0 drivers/tty/serial/serial_core.c:1023
 tty_tiocsserial drivers/tty/tty_io.c:2506 [inline]
 tty_ioctl+0xf60/0x14f0 drivers/tty/tty_io.c:2648
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440219
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe4d9e7ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440219
RDX: 0000000020000240 RSI: 000000000000541f RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000401b30 R11: 0000000000000246 R12: 0000000000401aa0
R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
CR2: 0000000000000002
---[ end trace 3a7aebb81a9b5361 ]---
RIP: 0010:writew arch/x86/include/asm/io.h:66 [inline]
RIP: 0010:mem16_serial_out+0x6c/0x90 drivers/tty/serial/8250/8250_port.c:414
Code: b6 8d e9 00 00 00 49 8d 7d 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 19 48 63 db 49 03 5d 40 <66> 44 89 23 5b 41 5c 41 5d 5d c3 e8 d4 2d cf fd eb c2 e8 2d 2e cf
RSP: 0018:ffffc90001fa78e8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 1ffffffff182040e RSI: ffffffff83e397f6 RDI: ffffffff8c102070
RBP: ffffc90001fa7900 R08: ffff888095842080 R09: ffffed10144ce1c6
R10: ffffed10144ce1c5 R11: ffff8880a2670e2b R12: 0000000000000001
R13: ffffffff8c102030 R14: ffffc90001fa7a40 R15: ffffffff8c102188
FS:  000000000177c880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 00000000a6ab1000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/12/20 01:51 upstream 4a94c4332334 36650b4b .config console log report syz C ci-upstream-kasan-gce-root
2019/12/19 18:54 upstream 4a94c4332334 36650b4b .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/10 00:02 upstream e42617b825f8 b31eda3d .config console log report syz C ci-upstream-kasan-gce-selinux-root
2019/12/09 18:19 upstream e42617b825f8 b31eda3d .config console log report syz C ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.