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AJvYcCUQmYzL8oCyKvruf3j6x1OTf11mSX2Do1EXASeQ9DjhBQ6yy4Ez0WxTiE6GTIrNs5x8DD4mCWwmzNraHP0=@vger.kernel.org X-Gm-Message-State: AOJu0YwjJ5recsF2BNwRSXi9gnLTX7DRqswXa8uK1P7V85QFWsmIgMPE Q7zdgW8xBVNkbaQISz6GxSShkCOsbIXH3UcoTJOV9CLYv7fmAF3uP3twqaSegz5a3XOuk67R1Si KLBNmJpPA+Mje7XuEqVcn5ha9StrYk2q9MeYgS42SJ5avqDjdkhg+Oek/i6Y= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:490d:b0:660:fdef:87c7 with SMTP id 006d021491bc7-662e0a8ae10mr1258156eaf.41.1769407444569; Sun, 25 Jan 2026 22:04:04 -0800 (PST) Date: Sun, 25 Jan 2026 22:04:04 -0800 In-Reply-To: <20260126054835.7392-1-kartikey406@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <697703d4.050a0220.1d05e9.000e.GAE@google.com> Subject: Re: [syzbot] [comedi?] BUG: unable to handle kernel paging request in dt2815_attach From: syzbot To: kartikey406@gmail.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: BUG: unable to handle kernel NULL pointer dereference in dt2815_attach BUG: kernel NULL pointer dereference, address: 0000000000000390 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 365dc067 P4D 365dc067 PUD 0 Oops: Oops: 0002 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5841 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+0x4f3/0xa40 drivers/comedi/drivers/dt2815.c:179 Code: 24 4c 8d b8 d0 01 00 00 4c 89 fb 48 c1 eb 03 42 80 3c 2b 00 74 08 4c 89 ff e8 a9 00 4c f9 48 8b 04 24 8b 90 d0 01 00 00 ff c2 <31> 66 90 bf e8 03 00 00 be b8 0b 00 00 ba 02 00 00 00 e8 56 0a 9e RSP: 0018:ffffc90002befa88 EFLAGS: 00010206 RAX: ffff888040c87000 RBX: 1ffff11008190e3a RCX: 0000000000000000 RDX: 000000000000007e RSI: 0000000000000400 RDI: 0000000000000000 RBP: 0000000000000400 R08: 0000000000000dc0 R09: 00000000ffffffff R10: 000000000000000a R11: ffffffff81ae5bd0 R12: ffffc90002befc04 R13: dffffc0000000000 R14: ffffc90002befbc0 R15: ffff888040c871d0 FS: 00007fa9eb7d96c0(0000) GS:ffff88808cf1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000390 CR3: 00000000595eb000 CR4: 0000000000352ef0 Call Trace: 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: 0033:0x7fa9ea99acb9 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:00007fa9eb7d9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fa9eac15fa0 RCX: 00007fa9ea99acb9 RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000003 RBP: 00007fa9eaa08bf7 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa9eac16038 R14: 00007fa9eac15fa0 R15: 00007fff0dbc24e8 Modules linked in: CR2: 0000000000000390 ---[ end trace 0000000000000000 ]--- RIP: 0010:__outb arch/x86/include/asm/shared/io.h:22 [inline] RIP: 0010:dt2815_attach+0x4f3/0xa40 drivers/comedi/drivers/dt2815.c:179 Code: 24 4c 8d b8 d0 01 00 00 4c 89 fb 48 c1 eb 03 42 80 3c 2b 00 74 08 4c 89 ff e8 a9 00 4c f9 48 8b 04 24 8b 90 d0 01 00 00 ff c2 <31> 66 90 bf e8 03 00 00 be b8 0b 00 00 ba 02 00 00 00 e8 56 0a 9e RSP: 0018:ffffc90002befa88 EFLAGS: 00010206 RAX: ffff888040c87000 RBX: 1ffff11008190e3a RCX: 0000000000000000 RDX: 000000000000007e RSI: 0000000000000400 RDI: 0000000000000000 RBP: 0000000000000400 R08: 0000000000000dc0 R09: 00000000ffffffff R10: 000000000000000a R11: ffffffff81ae5bd0 R12: ffffc90002befc04 R13: dffffc0000000000 R14: ffffc90002befbc0 R15: ffff888040c871d0 FS: 00007fa9eb7d96c0(0000) GS:ffff88808cf1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000390 CR3: 00000000595eb000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 24 4c and $0x4c,%al 2: 8d b8 d0 01 00 00 lea 0x1d0(%rax),%edi 8: 4c 89 fb mov %r15,%rbx b: 48 c1 eb 03 shr $0x3,%rbx f: 42 80 3c 2b 00 cmpb $0x0,(%rbx,%r13,1) 14: 74 08 je 0x1e 16: 4c 89 ff mov %r15,%rdi 19: e8 a9 00 4c f9 call 0xf94c00c7 1e: 48 8b 04 24 mov (%rsp),%rax 22: 8b 90 d0 01 00 00 mov 0x1d0(%rax),%edx 28: ff c2 inc %edx * 2a: 31 66 90 xor %esp,-0x70(%rsi) <-- trapping instruction 2d: bf e8 03 00 00 mov $0x3e8,%edi 32: be b8 0b 00 00 mov $0xbb8,%esi 37: ba 02 00 00 00 mov $0x2,%edx 3c: e8 .byte 0xe8 3d: 56 push %rsi 3e: 0a .byte 0xa 3f: 9e sahf Tested on: commit: 63804fed Linux 6.19-rc7 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1083f294580000 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=164bfe8a580000