syzbot


BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out
Status: upstream: reported C repro on 2019/12/08 23:44
Reported-by: syzbot+7c69b16d09d4fd344155@syzkaller.appspotmail.com
First crash: 900d, last: 618d

Fix bisection: failed (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 mem16_serial_out C inconclusive 2 709d 900d 0/1 upstream: reported C repro on 2019/12/08 23:15
upstream BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out C done 4 889d 899d 0/22 closed as dup on 2019/12/13 09:05

Sample crash report:
audit: type=1400 audit(1576761396.951:36): avc:  denied  { map } for  pid=7706 comm="syz-executor921" path="/root/syz-executor921592375" dev="sda1" ino=16484 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 0000000000000002
PGD 928aa067 P4D 928aa067 PUD 8fa2f067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7706 Comm: syz-executor921 Not tainted 4.19.90-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:413
Code: b6 8d e1 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 54 55 f1 fd eb c2 e8 ad 55 f1
RSP: 0018:ffff8880957c7830 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 1ffffffff16da20a RSI: ffffffff83b18446 RDI: ffffffff8b6d1050
RBP: ffff8880957c7848 R08: ffff888095c740c0 R09: ffffed10148081d6
R10: ffffed10148081d5 R11: ffff8880a4040eab R12: 0000000000000001
R13: ffffffff8b6d1010 R14: ffffffff8b6d1160 R15: ffff8880a4040b00
FS:  000000000157e880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000009252f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 serial_out drivers/tty/serial/8250/8250.h:116 [inline]
 serial8250_clear_fifos.part.0+0x3a/0xb0 drivers/tty/serial/8250/8250_port.c:556
 serial8250_clear_fifos drivers/tty/serial/8250/8250_port.c:555 [inline]
 serial8250_do_startup+0x440/0x1f90 drivers/tty/serial/8250/8250_port.c:2194
 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+0x488/0x970 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/0x2a50 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:00007ffecd856228 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 7be284f6278fc3bb ]---
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:413
Code: b6 8d e1 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 54 55 f1 fd eb c2 e8 ad 55 f1
RSP: 0018:ffff8880957c7830 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: 1ffffffff16da20a RSI: ffffffff83b18446 RDI: ffffffff8b6d1050
RBP: ffff8880957c7848 R08: ffff888095c740c0 R09: ffffed10148081d6
R10: ffffed10148081d5 R11: ffff8880a4040eab R12: 0000000000000001
R13: ffffffff8b6d1010 R14: ffffffff8b6d1160 R15: ffff8880a4040b00
FS:  000000000157e880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000009252f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-19 2019/12/19 13:19 linux-4.19.y 7d120bf21c05 79b211f7 .config log report syz C
ci2-linux-4-19 2019/12/08 23:43 linux-4.19.y fb683b5e3f53 1508f453 .config log report syz C