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UBSAN: shift-out-of-bounds in pcl726_attach

Status: upstream: reported C repro on 2025/07/08 03:45
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+2d6fd444c6491140f297@syzkaller.appspotmail.com
Fix commit: bab220b0bb5a comedi: pcl726: Prevent invalid irq number
Patched on: [ci2-linux-5-15-kasan ci2-linux-5-15-kasan-perf], missing on: [ci2-linux-5-15-kasan-arm64]
First crash: 128d, last: 78d
Fix bisection: fixed by (bisect log) :
commit bab220b0bb5af652007e278e8e8357f952b0e1ea
Author: Edward Adam Davis <eadavis@qq.com>
Date: Mon Jul 7 12:39:58 2025 +0000

  comedi: pcl726: Prevent invalid irq number

  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/07/08 upstream (ToT) d7b8f8e20813 C [report] UBSAN: shift-out-of-bounds in pcl726_attach
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 UBSAN: shift-out-of-bounds in pcl726_attach -1 C done 16 77d 105d 3/3 fixed on 2025/10/06 10:35
linux-6.6 UBSAN: shift-out-of-bounds in pcl726_attach origin:upstream -1 C done 17 77d 105d 2/2 fixed on 2025/10/06 10:09
upstream UBSAN: shift-out-of-bounds in pcl726_attach comedi -1 C 318 82d 131d 29/29 fixed on 2025/10/09 01:15
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2025/10/02 07:22 21m retest repro linux-5.15.y OK log
2025/10/02 07:22 15m retest repro linux-5.15.y OK log
2025/10/02 07:22 22m retest repro linux-5.15.y OK log
2025/07/24 05:51 13m retest repro linux-5.15.y report log
2025/07/24 05:51 13m retest repro linux-5.15.y report log
2025/07/24 05:51 11m retest repro linux-5.15.y report log

Sample crash report:
================================================================================
UBSAN: shift-out-of-bounds in drivers/comedi/drivers/pcl726.c:332:46
shift exponent -4 is negative
CPU: 0 PID: 4992 Comm: syz.3.182 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x37c/0x400 lib/ubsan.c:321
 pcl726_attach+0xab5/0xd40 drivers/comedi/drivers/pcl726.c:332
 comedi_device_attach+0x515/0x650 drivers/comedi/drivers.c:996
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:851 [inline]
 comedi_unlocked_ioctl+0x5ec/0xe90 drivers/comedi/comedi_fops.c:2131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f025b1f7be9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f025945f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f025b41efa0 RCX: 00007f025b1f7be9
RDX: 00002000000005c0 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f025b27ae19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f025b41f038 R14: 00007f025b41efa0 R15: 00007ffe1d712cf8
 </TASK>
================================================================================

Crashes (19):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/28 01:57 linux-5.15.y c79648372d02 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/28 01:57 linux-5.15.y c79648372d02 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/19 10:35 linux-5.15.y c79648372d02 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/18 06:58 linux-5.15.y c79648372d02 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/18 06:57 linux-5.15.y c79648372d02 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 20:13 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 20:13 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 09:24 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 09:23 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 09:04 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/06 09:04 linux-5.15.y c79648372d02 ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/05 08:36 linux-5.15.y c79648372d02 f5bcc8dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/08/05 08:36 linux-5.15.y c79648372d02 f5bcc8dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/31 13:32 linux-5.15.y c79648372d02 f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/31 13:31 linux-5.15.y c79648372d02 f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/08 06:41 linux-5.15.y 3dea0e7f549e 4f67c4ae .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/08 05:41 linux-5.15.y 3dea0e7f549e 4f67c4ae .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/08 04:44 linux-5.15.y 3dea0e7f549e 4f67c4ae .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
2025/07/08 03:45 linux-5.15.y 3dea0e7f549e 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan UBSAN: shift-out-of-bounds in pcl726_attach
* Struck through repros no longer work on HEAD.