[moderation] [mm?] KCSAN: data-race in copy_process / show_stat (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8fde5d1d47f6 Merge tag 'acpi-7.1-rc6' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13b9452e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f571f22917457cd8
dashboard link: https://syzkaller.appspot.com/bug?extid=c95c682a0d287dbbb481
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ak...@linux-foundation.org bse...@google.com da...@kernel.org dietmar....@arm.com juri....@redhat.com ke...@kernel.org kpratee...@amd.com li...@infradead.org linux-...@vger.kernel.org linu...@kvack.org l...@kernel.org mgo...@suse.de mho...@suse.com mi...@redhat.com pet...@infradead.org ros...@goodmis.org rp...@kernel.org sur...@google.com vba...@kernel.org vincent...@linaro.org vsch...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6fd7078e6720/disk-8fde5d1d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8a314316afc1/vmlinux-8fde5d1d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c0f4649947fb/bzImage-8fde5d1d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c95c68...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in copy_process / show_stat

read-write to 0xffffffff89368ae0 of 8 bytes by task 15138 on cpu 0:
copy_process+0x21f6/0x2370 kernel/fork.c:2510
kernel_clone+0x1c0/0x5f0 kernel/fork.c:2722
__do_sys_clone kernel/fork.c:2863 [inline]
__se_sys_clone kernel/fork.c:2847 [inline]
__x64_sys_clone+0x143/0x180 kernel/fork.c:2847
x64_sys_call+0x1222/0x3020 arch/x86/include/generated/asm/syscalls_64.h:57
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff89368ae0 of 8 bytes by task 15131 on cpu 1:
show_stat+0xc16/0xd80 fs/proc/stat.c:181
seq_read_iter+0x31e/0x940 fs/seq_file.c:231
proc_reg_read_iter+0xe6/0x180 fs/proc/inode.c:295
copy_splice_read+0x471/0x6c0 fs/splice.c:362
do_splice_read fs/splice.c:980 [inline]
splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
do_splice_direct_actor fs/splice.c:1202 [inline]
do_splice_direct+0x119/0x1a0 fs/splice.c:1228
do_sendfile+0x382/0x650 fs/read_write.c:1372
__do_sys_sendfile64 fs/read_write.c:1433 [inline]
__se_sys_sendfile64 fs/read_write.c:1419 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000003b23 -> 0x0000000000003b24

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15131 Comm: syz.0.2819 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================


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