KCSAN: data-race in release_sock / sk_clone

Status: auto-obsoleted due to no activity on 2026/07/31 21:15
Subsystems: net
Labels: prio:high race:benign
[Documentation on labels]
First crash: 92d, last: 92d
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
44b930e3 assessment-kcsan Benign: ✅ KCSAN: data-race in release_sock / sk_clone 2026/06/09 12:38 2026/06/09 12:38 2026/06/09 13:21 c36c07f6
f028ed63 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ KCSAN: data-race in release_sock / sk_clone 2026/06/09 12:35 2026/06/09 12:35 2026/06/09 13:03 c36c07f6

Sample crash report:
==================================================================
BUG: KCSAN: data-race in release_sock / sk_clone

write to 0xffff88810aa4db48 of 4 bytes by task 12651 on cpu 0:
 sock_release_ownership include/net/sock.h:1824 [inline]
 release_sock+0xd9/0x180 net/core/sock.c:3825
 inet_csk_accept+0x112/0x630 net/ipv4/inet_connection_sock.c:708
 inet_accept+0x65/0xc0 net/ipv4/af_inet.c:794
 kernel_accept+0x110/0x270 net/socket.c:3705
 rds_tcp_accept_one+0xf2/0x8a0 net/rds/tcp_listen.c:177
 rds_tcp_accept_worker+0x1a/0x60 net/rds/tcp.c:533
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88810aa4da84 of 2428 bytes by interrupt on cpu 1:
 sock_copy net/core/sock.c:2223 [inline]
 sk_clone+0xce/0xa40 net/core/sock.c:2487
 sk_clone_lock include/net/sock.h:1848 [inline]
 inet_csk_clone_lock+0x28/0x270 net/ipv4/inet_connection_sock.c:1199
 tcp_create_openreq_child+0x32/0x1300 net/ipv4/tcp_minisocks.c:551
 tcp_v4_syn_recv_sock+0xbf/0xab0 net/ipv4/tcp_ipv4.c:1694
 tcp_v6_syn_recv_sock+0xa8/0xbf0 net/ipv6/tcp_ipv6.c:1388
 tcp_check_req+0xddf/0x1150 net/ipv4/tcp_minisocks.c:926
 tcp_v4_rcv+0xefe/0x1c10 net/ipv4/tcp_ipv4.c:2164
 ip_protocol_deliver_rcu+0x395/0x790 net/ipv4/ip_input.c:207
 ip_local_deliver_finish+0x1fc/0x2f0 net/ipv4/ip_input.c:241
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip_local_deliver+0xe8/0x1e0 net/ipv4/ip_input.c:262
 dst_input include/net/dst.h:480 [inline]
 ip_rcv_finish+0x188/0x1a0 net/ipv4/ip_input.c:492
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip_rcv+0x62/0x160 net/ipv4/ip_input.c:612
 __netif_receive_skb_one_core net/core/dev.c:6202 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0x341/0x670 net/core/dev.c:6666
 __napi_poll+0x61/0x300 net/core/dev.c:7733
 napi_poll net/core/dev.c:7796 [inline]
 net_rx_action+0x452/0x930 net/core/dev.c:7953
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 do_softirq+0x45/0x60 kernel/softirq.c:523
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:912 [inline]
 __dev_queue_xmit+0x1396/0x1ec0 net/core/dev.c:4905
 dev_queue_xmit include/linux/netdevice.h:3418 [inline]
 neigh_hh_output include/net/neighbour.h:544 [inline]
 neigh_output include/net/neighbour.h:558 [inline]
 ip_finish_output2+0x705/0x8c0 net/ipv4/ip_output.c:237
 __ip_finish_output net/ipv4/ip_output.c:-1 [inline]
 ip_finish_output+0x112/0x290 net/ipv4/ip_output.c:325
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip_output+0xbd/0x1c0 net/ipv4/ip_output.c:438
 dst_output include/net/dst.h:470 [inline]
 ip_local_out net/ipv4/ip_output.c:131 [inline]
 __ip_queue_xmit+0xb68/0xba0 net/ipv4/ip_output.c:534
 ip_queue_xmit+0x39/0x50 net/ipv4/ip_output.c:548
 __tcp_transmit_skb+0x1c2a/0x20b0 net/ipv4/tcp_output.c:1715
 __tcp_send_ack+0x288/0x3b0 net/ipv4/tcp_output.c:4500
 tcp_send_ack_reflect_ect+0x61/0x70 net/ipv4/tcp_input.c:4038
 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6969 [inline]
 tcp_rcv_state_process+0x1e6f/0x21f0 net/ipv4/tcp_input.c:7164
 tcp_v4_do_rcv+0x5a5/0xa40 net/ipv4/tcp_ipv4.c:1873
 sk_backlog_rcv include/net/sock.h:1190 [inline]
 __release_sock+0x15e/0x2f0 net/core/sock.c:3220
 release_sock+0x125/0x180 net/core/sock.c:3819
 inet_stream_connect+0x57/0x70 net/ipv4/af_inet.c:756
 kernel_connect+0x9f/0xf0 net/socket.c:3740
 rds_tcp_conn_path_connect+0x50d/0x5f0 net/rds/tcp_connect.c:205
 rds_connect_worker+0x12f/0x1b0 net/rds/threads.c:176
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 30 Comm: kworker/u8:1 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: krds_cp_wq#6/0 rds_connect_worker
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/05 20:33 upstream ddd664bbff63 48b6c3fa .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in release_sock / sk_clone
* Struck through repros no longer work on HEAD.