From: syzbot <syzbot+c18de0ad13d62f18469d@syzkaller.appspotmail.com>
To: Liam.Howlett@oracle.com, akpm@linux-foundation.org,
david@kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, ljs@kernel.org, mhocko@suse.com,
rppt@kernel.org, surenb@google.com,
syzkaller-bugs@googlegroups.com, vbabka@kernel.org
Subject: [syzbot] [mm?] KMSAN: uninit-value in copy_from_kernel_nofault
Date: Mon, 16 Mar 2026 03:22:46 -0700 [thread overview]
Message-ID: <69b7d9f6.050a0220.248e02.0112.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 80234b5ab240 Merge tag 'rproc-v7.0-fixes' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1474cd52580000
kernel config: https://syzkaller.appspot.com/x/.config?x=242f02fcd3fbc8f3
dashboard link: https://syzkaller.appspot.com/bug?extid=c18de0ad13d62f18469d
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a0d037332dff/disk-80234b5a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0a1f7f8b54f8/vmlinux-80234b5a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83eb68ee6421/bzImage-80234b5a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c18de0ad13d62f18469d@syzkaller.appspotmail.com
=====================================================
BUG: KMSAN: uninit-value in copy_from_kernel_nofault+0x15f/0x570 mm/maccess.c:41
copy_from_kernel_nofault+0x15f/0x570 mm/maccess.c:41
prepend_copy fs/d_path.c:50 [inline]
prepend fs/d_path.c:76 [inline]
prepend_name fs/d_path.c:101 [inline]
__prepend_path fs/d_path.c:133 [inline]
prepend_path+0x64e/0x1090 fs/d_path.c:172
d_absolute_path+0x11b/0x240 fs/d_path.c:234
tomoyo_get_absolute_path security/tomoyo/realpath.c:101 [inline]
tomoyo_realpath_from_path+0x4bd/0x9f0 security/tomoyo/realpath.c:271
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x249/0x9a0 security/tomoyo/file.c:827
tomoyo_inode_getattr+0x35/0x40 security/tomoyo/tomoyo.c:123
security_inode_getattr+0x16e/0x590 security/security.c:1869
vfs_getattr fs/stat.c:259 [inline]
vfs_fstat fs/stat.c:281 [inline]
__do_sys_newfstat fs/stat.c:551 [inline]
__se_sys_newfstat+0xd5/0xa60 fs/stat.c:546
__x64_sys_newfstat+0x78/0xb0 fs/stat.c:546
x64_sys_call+0x2f28/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:6
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
<Zero or more stacks not recorded to save memory>
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
copy_name fs/dcache.c:2861 [inline]
__d_move+0xf72/0x2aa0 fs/dcache.c:2930
d_move+0x71/0xf0 fs/dcache.c:2977
vfs_rename+0x2510/0x2650 fs/namei.c:6041
filename_renameat2+0xb7f/0x1260 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 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:4549 [inline]
slab_alloc_node mm/slub.c:4869 [inline]
kmem_cache_alloc_lru_noprof+0x382/0x1280 mm/slub.c:4888
__d_alloc+0x55/0xa00 fs/dcache.c:1740
d_alloc+0x57/0x300 fs/dcache.c:1819
lookup_one_qstr_excl+0x1a1/0x7b0 fs/namei.c:1801
__start_renaming+0x38e/0x870 fs/namei.c:3862
filename_renameat2+0x735/0x1260 fs/namei.c:6119
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0xc5/0x5d0 fs/namei.c:6184
__x64_sys_rename+0x78/0xb0 fs/namei.c:6184
x64_sys_call+0x329/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Bytes 5-7 of 8 are uninitialized
Memory access of size 8 starts at ffff888014109578
CPU: 0 UID: 0 PID: 5966 Comm: udevd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
=====================================================
---
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next reply other threads:[~2026-03-16 10:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 10:22 syzbot [this message]
2026-03-16 11:58 ` [syzbot] [mm?] KMSAN: uninit-value in copy_from_kernel_nofault Christian Brauner
2026-03-16 12:44 ` vbabka
2026-03-16 14:36 ` Alexander Potapenko
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