KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data

KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet

Status: upstream: reported on 2026/01/07 15:34
Subsystems: afs net
[Documentation on labels]
Reported-by: syzbot+6182afad5045e6703b3d@syzkaller.appspotmail.com
Fix commit: 5d5fe8bcd331 rxrpc: Fix data-race warning and potential load/store tearing
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-upstream-gce-arm64]
First crash: 92d, last: 92d

▶ ▼ ✨ AI Jobs (1)

ID	Workflow	Result	Correct	Bug	Created	Started	Finished	Revision	Error
4dd997bd-133b-49be-9af7-d0fa3ae089f0	assessment-kcsan	Benign: ✅ Confident: ✅	❓	KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet	2026/01/15 16:32	2026/01/15 16:32	2026/01/15 16:35	a9d6a79219801d2130df3b1a792c57f0e5428e9f

▶ ▼ Discussions (5)

Title	Replies (including bot)	Last reply
[PATCH 6.6.y] rxrpc: Fix data-race warning and potential load/store tearing	1 (1)	2026/02/27 00:54
[PATCH net v3] rxrpc: Fix data-race warning and potential load/store tearing	2 (2)	2026/01/22 04:10
[PATCH net v2] rxrpc: Fix data-race warning and potential load/store tearing	1 (1)	2026/01/14 21:36
[PATCH] rxrpc: Fix data-race warning and potential load/store tearing	4 (4)	2026/01/14 03:31
[syzbot] [afs?] [net?] KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet	3 (4)	2026/01/08 14:28

Sample crash report:

==================================================================
BUG: KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet

write to 0xffff8881044ab560 of 8 bytes by task 4063 on cpu 1:
 rxrpc_send_data_packet+0x1593/0x1df0 net/rxrpc/output.c:714
 rxrpc_transmit_fresh_data net/rxrpc/call_event.c:255 [inline]
 rxrpc_transmit_some_data+0x63c/0x8b0 net/rxrpc/call_event.c:277
 rxrpc_input_call_event+0x8bb/0xf30 net/rxrpc/call_event.c:401
 rxrpc_io_thread+0x1c1e/0x21c0 net/rxrpc/io_thread.c:550
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881044ab560 of 8 bytes by task 3500 on cpu 0:
 rxrpc_peer_keepalive_dispatch net/rxrpc/peer_event.c:268 [inline]
 rxrpc_peer_keepalive_worker+0x44e/0x800 net/rxrpc/peer_event.c:341
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000000 -> 0x0000000000000029

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3500 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: krxrpcd rxrpc_peer_keepalive_worker
==================================================================

Crashes (1):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2025/11/26 21:30	upstream	30f09200cc4a	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet

* ~~Struck through~~ repros no longer work on HEAD.