syzbot


KMSAN: kernel-infoleak in do_insnlist_ioctl

Status: upstream: reported on 2025/07/21 19:30
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+fb4362a104d45ab09cf9@syzkaller.appspotmail.com
First crash: 5d12h, last: 5d12h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] KMSAN: kernel-infoleak in do_insnlist_ioctl 0 (1) 2025/07/21 19:30

Sample crash report:
=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in _inline_copy_to_user include/linux/uaccess.h:196 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xcc/0x120 lib/usercopy.c:26
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 _inline_copy_to_user include/linux/uaccess.h:196 [inline]
 _copy_to_user+0xcc/0x120 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:225 [inline]
 do_insnlist_ioctl+0x596/0x890 drivers/comedi/comedi_fops.c:1572
 comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x239/0x400 fs/ioctl.c:893
 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
 x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x95f/0x1310 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kmalloc_array_noprof include/linux/slab.h:948 [inline]
 do_insnlist_ioctl+0x1b2/0x890 drivers/comedi/comedi_fops.c:1551
 comedi_unlocked_ioctl+0x1c6b/0x1e00 drivers/comedi/comedi_fops.c:2253
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x239/0x400 fs/ioctl.c:893
 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
 x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Bytes 4-583 of 584 are uninitialized
Memory access of size 584 starts at ffff888053394400

CPU: 1 UID: 0 PID: 22163 Comm: syz.9.4290 Not tainted 6.16.0-rc6-syzkaller-00037-ge2291551827f #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
=====================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/17 19:20 upstream e2291551827f 0d1223f1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: kernel-infoleak in do_insnlist_ioctl
2025/07/17 19:21 upstream e2291551827f 0d1223f1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: kernel-infoleak-after-free in do_insnlist_ioctl
* Struck through repros no longer work on HEAD.