[moderation] [bpf?] KCSAN: data-race in __bpf_lru_node_move / bpf_lru_push_free (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4c06e63b9203 Merge tag 'for-6.16-rc4-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11374c8c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=eea96b85b0259840
dashboard link: https://syzkaller.appspot.com/bug?extid=64f9e87c9b1e0427e03b
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [and...@kernel.org a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net edd...@gmail.com hao...@google.com john.fa...@gmail.com jo...@kernel.org kps...@kernel.org linux-...@vger.kernel.org marti...@linux.dev s...@fomichev.me so...@kernel.org yongho...@linux.dev]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a29ad39ab029/disk-4c06e63b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccd884b8dad2/vmlinux-4c06e63b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/96b61fc8e436/bzImage-4c06e63b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+64f9e8...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __bpf_lru_node_move / bpf_lru_push_free

write to 0xffff8881187845ca of 1 bytes by task 19088 on cpu 0:
__bpf_lru_node_move+0xdc/0x1f0 kernel/bpf/bpf_lru_list.c:116
__bpf_lru_list_rotate_active kernel/bpf/bpf_lru_list.c:-1 [inline]
__bpf_lru_list_rotate+0xb4/0x270 kernel/bpf/bpf_lru_list.c:245
bpf_lru_list_pop_free_to_local kernel/bpf/bpf_lru_list.c:334 [inline]
bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:452 [inline]
bpf_lru_pop_free+0x4ce/0xcd0 kernel/bpf/bpf_lru_list.c:504
prealloc_lru_pop kernel/bpf/hashtab.c:303 [inline]
htab_lru_map_update_elem+0xc5/0x6f0 kernel/bpf/hashtab.c:1216
bpf_map_update_value+0x354/0x3a0 kernel/bpf/syscall.c:290
generic_map_update_batch+0x3f5/0x540 kernel/bpf/syscall.c:1982
bpf_map_do_batch+0x258/0x380 kernel/bpf/syscall.c:5344
__sys_bpf+0x2e0/0x790 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:5943 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5941 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:5941
x64_sys_call+0x2478/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881187845ca of 1 bytes by task 19083 on cpu 1:
bpf_lru_list_push_free kernel/bpf/bpf_lru_list.c:315 [inline]
bpf_common_lru_push_free kernel/bpf/bpf_lru_list.c:538 [inline]
bpf_lru_push_free+0x578/0x590 kernel/bpf/bpf_lru_list.c:561
htab_lru_push_free kernel/bpf/hashtab.c:1183 [inline]
htab_lru_map_update_elem+0x59e/0x6f0 kernel/bpf/hashtab.c:1248
bpf_map_update_value+0x354/0x3a0 kernel/bpf/syscall.c:290
generic_map_update_batch+0x3f5/0x540 kernel/bpf/syscall.c:1982
bpf_map_do_batch+0x258/0x380 kernel/bpf/syscall.c:5344
__sys_bpf+0x2e0/0x790 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:5943 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5941 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:5941
x64_sys_call+0x2478/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19083 Comm: syz.4.6964 Not tainted 6.16.0-rc4-syzkaller-00123-g4c06e63b9203 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.