[moderation] [bpf?] KCSAN: data-race in bpf_lru_pop_free / htab_lru_percpu_map_lookup_elem (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d79bc8f79baa Merge tag 'turbostat-2025.02.02' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16391764580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fdf6e93ff35d9650
dashboard link: https://syzkaller.appspot.com/bug?extid=040dd2b93e1c8a640783
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/34cf36cdba4d/disk-d79bc8f7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3c300efff58f/vmlinux-d79bc8f7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4762bda2dffc/bzImage-d79bc8f7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+040dd2...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in bpf_lru_pop_free / htab_lru_percpu_map_lookup_elem

write to 0xffff8881169567e8 of 4 bytes by task 13245 on cpu 1:
bpf_percpu_lru_pop_free kernel/bpf/bpf_lru_list.c:426 [inline]
bpf_lru_pop_free+0x197/0xd30 kernel/bpf/bpf_lru_list.c:502
prealloc_lru_pop kernel/bpf/hashtab.c:308 [inline]
__htab_lru_percpu_map_update_elem+0xfe/0x630 kernel/bpf/hashtab.c:1376
bpf_percpu_hash_update+0x5e/0xa0 kernel/bpf/hashtab.c:2446
bpf_map_update_value+0x2ab/0x3b0 kernel/bpf/syscall.c:265
generic_map_update_batch+0x401/0x520 kernel/bpf/syscall.c:1954
bpf_map_do_batch+0x28c/0x3f0 kernel/bpf/syscall.c:5302
__sys_bpf+0x2e5/0x7a0
__do_sys_bpf kernel/bpf/syscall.c:5901 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5899 [inline]
__x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5899
x64_sys_call+0x2914/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881169567e8 of 4 bytes by task 2968 on cpu 0:
lookup_nulls_elem_raw kernel/bpf/hashtab.c:667 [inline]
__htab_map_lookup_elem kernel/bpf/hashtab.c:697 [inline]
htab_lru_percpu_map_lookup_elem+0xb8/0x1c0 kernel/bpf/hashtab.c:2380
bpf_prog_67a7f92a6a5e5f13+0x43/0x47
bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
__bpf_prog_run include/linux/filter.h:701 [inline]
bpf_prog_run include/linux/filter.h:708 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
bpf_trace_run2+0x104/0x1d0 kernel/trace/bpf_trace.c:2412
__traceiter_kfree+0x2b/0x50 include/trace/events/kmem.h:94
__do_trace_kfree include/trace/events/kmem.h:94 [inline]
trace_kfree include/trace/events/kmem.h:94 [inline]
kfree+0x247/0x2f0 mm/slub.c:4744
usb_control_msg+0x214/0x240 drivers/usb/core/message.c:160
get_port_status drivers/usb/core/hub.c:605 [inline]
hub_ext_port_status+0xbf/0x480 drivers/usb/core/hub.c:622
usb_hub_port_status drivers/usb/core/hub.c:672 [inline]
port_event drivers/usb/core/hub.c:5716 [inline]
hub_event+0x538/0x2910 drivers/usb/core/hub.c:5905
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
kthread+0x4ae/0x520 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x9cdae4c1 -> 0xea173e13

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2968 Comm: kworker/0:2 Not tainted 6.13.0-syzkaller-10033-gd79bc8f79baa #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: usb_hub_wq hub_event
==================================================================


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[syzbot]

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