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BUG: unable to handle kernel NULL pointer dereference in mem_serial_out

Status: upstream: reported C repro on 2019/12/05 04:54
Reported-by: syzbot+fe6d97653a5ade9736e1@syzkaller.appspotmail.com
First crash: 1815d, last: 1532d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ 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 mem_serial_out C inconclusive 3 1629d 1815d 0/1 upstream: reported C repro on 2019/12/05 02:21
upstream BUG: unable to handle kernel NULL pointer dereference in mem_serial_out serial C done 7 1800d 1813d 0/28 closed as invalid on 2020/01/07 17:02
▶ ▼ Fix bisection attempts (10)
Created Duration User Patch Repo Result
2020/10/13 02:21 2m bisect fix linux-4.19.y error job log
2020/09/13 01:42 22m bisect fix linux-4.19.y OK (0) job log log
2020/08/14 01:15 27m bisect fix linux-4.19.y OK (0) job log log
2020/07/15 00:49 25m bisect fix linux-4.19.y OK (0) job log log
2020/06/15 00:23 25m bisect fix linux-4.19.y OK (0) job log log
2020/05/15 20:41 27m bisect fix linux-4.19.y OK (0) job log log
2020/04/15 19:58 26m bisect fix linux-4.19.y OK (0) job log log
2020/03/16 19:20 27m bisect fix linux-4.19.y OK (0) job log log
2020/02/15 18:18 25m bisect fix linux-4.19.y OK (0) job log log
2020/01/16 13:36 26m bisect fix linux-4.19.y OK (0) job log log

Sample crash report:
audit: type=1400 audit(1575967712.165:36): avc:  denied  { map } for  pid=7704 comm="syz-executor514" path="/root/syz-executor514321103" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
BUG: unable to handle kernel NULL pointer dereference at 0000000000000003
PGD 9e67c067 P4D 9e67c067 PUD 95f89067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7704 Comm: syz-executor514 Not tainted 4.19.88-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline]
RIP: 0010:mem_serial_out+0x70/0x90 drivers/tty/serial/8250/8250_port.c:407
Code: e1 00 00 00 49 8d 7c 24 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 5c 24 40 <44> 88 2b 5b 41 5c 41 5d 5d c3 e8 b1 6c f1 fd eb c0 e8 0a 6d f1 fd
RSP: 0018:ffff8880817b7850 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 1ffffffff16da3f7 RSI: ffffffff83b16516 RDI: ffffffff8b6d1fb8
RBP: ffff8880817b7868 R08: ffff88808f8124c0 R09: ffffed104327c1d6
R10: ffffed104327c1d5 R11: ffff8882193e0eab R12: ffffffff8b6d1f78
R13: 00000000000000bf R14: 000000000000000a R15: ffffffff8b6d1fc8
FS:  0000000001c47880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000003 CR3: 0000000098d60000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 serial_port_out include/linux/serial_core.h:273 [inline]
 serial8250_do_startup+0x1366/0x1fe0 drivers/tty/serial/8250/8250_port.c:2136
 serial8250_startup+0x62/0x80 drivers/tty/serial/8250/8250_port.c:2406
 uart_port_startup drivers/tty/serial/serial_core.c:218 [inline]
 uart_startup.part.0+0x491/0x980 drivers/tty/serial/serial_core.c:257
 uart_startup drivers/tty/serial/serial_core.c:254 [inline]
 uart_set_info drivers/tty/serial/serial_core.c:997 [inline]
 uart_set_info_user drivers/tty/serial/serial_core.c:1025 [inline]
 uart_ioctl+0x15ec/0x2a60 drivers/tty/serial/serial_core.c:1348
 tty_ioctl+0x7f3/0x1510 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 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:00007ffccb079d08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440219
RDX: 0000000020000080 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: 0000000000000003
---[ end trace 9f5b4c5cacb51795 ]---
RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline]
RIP: 0010:mem_serial_out+0x70/0x90 drivers/tty/serial/8250/8250_port.c:407
Code: e1 00 00 00 49 8d 7c 24 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 5c 24 40 <44> 88 2b 5b 41 5c 41 5d 5d c3 e8 b1 6c f1 fd eb c0 e8 0a 6d f1 fd
RSP: 0018:ffff8880817b7850 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 1ffffffff16da3f7 RSI: ffffffff83b16516 RDI: ffffffff8b6d1fb8
RBP: ffff8880817b7868 R08: ffff88808f8124c0 R09: ffffed104327c1d6
R10: ffffed104327c1d5 R11: ffff8882193e0eab R12: ffffffff8b6d1f78
R13: 00000000000000bf R14: 000000000000000a R15: ffffffff8b6d1fc8
FS:  0000000001c47880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000003 CR3: 0000000098d60000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/12/10 08:51 linux-4.19.y fb683b5e3f53 4b83c8fb .config console log report syz C ci2-linux-4-19
2019/12/05 04:53 linux-4.19.y 174651bdf802 b2088328 .config console log report syz C ci2-linux-4-19
2019/12/17 13:36 linux-4.19.y 312017a460d5 d13d7958 .config console log report ci2-linux-4-19
* Struck through repros no longer work on HEAD.