[moderation] [bpf?] KCSAN: data-race in __bpf_lru_list_rotate / bpf_lru_push_free (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9f2693489ef8 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c3772a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=a9df912d90719592f2fd
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/2447c3f73254/disk-9f269348.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/62bd191e32ba/vmlinux-9f269348.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6ac4ad5ed01e/bzImage-9f269348.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a9df91...@syzkaller.appspotmail.com

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

write to 0xffff8881056adc6a of 1 bytes by task 5115 on cpu 0:
__bpf_lru_node_move kernel/bpf/bpf_lru_list.c:108 [inline]
__bpf_lru_list_rotate_active kernel/bpf/bpf_lru_list.c:148 [inline]
__bpf_lru_list_rotate+0x2ec/0x780 kernel/bpf/bpf_lru_list.c:237
bpf_lru_list_pop_free_to_local kernel/bpf/bpf_lru_list.c:326 [inline]
bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:444 [inline]
bpf_lru_pop_free+0x640/0xe40 kernel/bpf/bpf_lru_list.c:496
prealloc_lru_pop kernel/bpf/hashtab.c:299 [inline]
htab_lru_map_update_elem+0xc6/0x700 kernel/bpf/hashtab.c:1215
bpf_map_update_value+0x4f3/0x570 kernel/bpf/syscall.c:294
generic_map_update_batch+0x3eb/0x540 kernel/bpf/syscall.c:2038
bpf_map_do_batch+0x25c/0x380 kernel/bpf/syscall.c:5647
__sys_bpf+0x5f8/0x7b0 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881056adc6a of 1 bytes by task 5114 on cpu 1:
bpf_lru_list_push_free kernel/bpf/bpf_lru_list.c:307 [inline]
bpf_common_lru_push_free kernel/bpf/bpf_lru_list.c:530 [inline]
bpf_lru_push_free+0x578/0x590 kernel/bpf/bpf_lru_list.c:553
htab_lru_push_free kernel/bpf/hashtab.c:1183 [inline]
htab_lru_map_update_elem+0x5a4/0x700 kernel/bpf/hashtab.c:1247
bpf_map_update_value+0x4f3/0x570 kernel/bpf/syscall.c:294
generic_map_update_batch+0x3eb/0x540 kernel/bpf/syscall.c:2038
bpf_map_do_batch+0x25c/0x380 kernel/bpf/syscall.c:5647
__sys_bpf+0x5f8/0x7b0 kernel/bpf/syscall.c:-1
__do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 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: 5114 Comm: syz.0.477 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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