From: syzbot <syzbot+72f94b474d6e50b71ffc@syzkaller.appspotmail.com>
To: kartikey406@gmail.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [comedi?] BUG: unable to handle kernel paging request in dt2815_attach
Date: Sun, 25 Jan 2026 22:33:02 -0800 [thread overview]
Message-ID: <69770a9e.a00a0220.33ccc7.0033.GAE@google.com> (raw)
In-Reply-To: <20260126061729.9345-1-kartikey406@gmail.com>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in dt2815_attach
dt2815: [PID 5821] ENTER dt2815_attach, it->options[0] = 0x7d
dt2815: [PID 5821] after comedi_request_region, dev->iobase = 0x7d
dt2815: [PID 5821] About to do FIRST outb, dev = ffff888040506800, dev->iobase = 0x7d
BUG: unable to handle page fault for address: 000000007fffff90
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 57fb4067 P4D 57fb4067 PUD 0
Oops: Oops: 0002 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5821 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__outb arch/x86/include/asm/shared/io.h:22 [inline]
RIP: 0010:dt2815_attach+0x6e0/0x1110 drivers/comedi/drivers/dt2815.c:187
Code: f5 ff 48 bd 00 00 00 00 00 fc ff df 41 80 3c 2c 00 74 12 4c 89 f7 e8 9f 02 f9 00 48 bd 00 00 00 00 00 fc ff df 41 8b 16 ff c2 <31> 66 90 41 0f b6 44 2d 00 84 c0 0f 85 00 08 00 00 8b 33 48 c7 c7
RSP: 0018:ffffc90002a8fa78 EFLAGS: 00010206
RAX: 0000000000000055 RBX: ffff88803405cf98 RCX: c9cdd809989aea00
RDX: 000000000000007e RSI: 0000000080000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff88801fc247d3 R09: 1ffff11003f848fa
R10: dffffc0000000000 R11: ffffed1003f848fb R12: 1ffff110080a0d3a
R13: 1ffff1100680b9f3 R14: ffff8880405069d0 R15: ffff888040506800
FS: 00007f8323dfe6c0(0000) GS:ffff88808cf1b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000007fffff90 CR3: 0000000057ff9000 CR4: 0000000000352ef0
Call Trace:
<TASK>
comedi_device_attach+0x51f/0x720 drivers/comedi/drivers.c:1069
do_devconfig_ioctl drivers/comedi/comedi_fops.c:928 [inline]
comedi_unlocked_ioctl+0x701/0x1240 drivers/comedi/comedi_fops.c:2240
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f832479acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8323dfe028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8324a15fa0 RCX: 00007f832479acb9
RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f8324808bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8324a16038 R14: 00007f8324a15fa0 R15: 00007fff45a7cad8
</TASK>
Modules linked in:
CR2: 000000007fffff90
---[ end trace 0000000000000000 ]---
RIP: 0010:__outb arch/x86/include/asm/shared/io.h:22 [inline]
RIP: 0010:dt2815_attach+0x6e0/0x1110 drivers/comedi/drivers/dt2815.c:187
Code: f5 ff 48 bd 00 00 00 00 00 fc ff df 41 80 3c 2c 00 74 12 4c 89 f7 e8 9f 02 f9 00 48 bd 00 00 00 00 00 fc ff df 41 8b 16 ff c2 <31> 66 90 41 0f b6 44 2d 00 84 c0 0f 85 00 08 00 00 8b 33 48 c7 c7
RSP: 0018:ffffc90002a8fa78 EFLAGS: 00010206
RAX: 0000000000000055 RBX: ffff88803405cf98 RCX: c9cdd809989aea00
RDX: 000000000000007e RSI: 0000000080000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff88801fc247d3 R09: 1ffff11003f848fa
R10: dffffc0000000000 R11: ffffed1003f848fb R12: 1ffff110080a0d3a
R13: 1ffff1100680b9f3 R14: ffff8880405069d0 R15: ffff888040506800
FS: 00007f8323dfe6c0(0000) GS:ffff88808cf1b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000007fffff90 CR3: 0000000057ff9000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: f5 cmc
1: ff 48 bd decl -0x43(%rax)
4: 00 00 add %al,(%rax)
6: 00 00 add %al,(%rax)
8: 00 fc add %bh,%ah
a: ff lcall (bad)
b: df 41 80 filds -0x80(%rcx)
e: 3c 2c cmp $0x2c,%al
10: 00 74 12 4c add %dh,0x4c(%rdx,%rdx,1)
14: 89 f7 mov %esi,%edi
16: e8 9f 02 f9 00 call 0xf902ba
1b: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp
22: fc ff df
25: 41 8b 16 mov (%r14),%edx
28: ff c2 inc %edx
* 2a: 31 66 90 xor %esp,-0x70(%rsi) <-- trapping instruction
2d: 41 0f b6 44 2d 00 movzbl 0x0(%r13,%rbp,1),%eax
33: 84 c0 test %al,%al
35: 0f 85 00 08 00 00 jne 0x83b
3b: 8b 33 mov (%rbx),%esi
3d: 48 rex.W
3e: c7 .byte 0xc7
3f: c7 .byte 0xc7
Tested on:
commit: 63804fed Linux 6.19-rc7
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d6905a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e2e5d7c9c1e01cf4
dashboard link: https://syzkaller.appspot.com/bug?extid=72f94b474d6e50b71ffc
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=16a40a44580000
next parent reply other threads:[~2026-01-26 6:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260126061729.9345-1-kartikey406@gmail.com>
2026-01-26 6:33 ` syzbot [this message]
[not found] <20260126064243.10298-1-kartikey406@gmail.com>
2026-01-26 7:04 ` [syzbot] [comedi?] BUG: unable to handle kernel paging request in dt2815_attach syzbot
[not found] <20260126054835.7392-1-kartikey406@gmail.com>
2026-01-26 6:04 ` syzbot
[not found] <20260126051936.5684-1-kartikey406@gmail.com>
2026-01-26 5:36 ` syzbot
2026-01-24 6:45 syzbot
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