syzbot


KCSAN: data-race in __tipc_sendstream / tipc_poll (3)

Status: moderation: reported on 2026/01/12 16:22
Subsystems: tipc
[Documentation on labels]
Reported-by: syzbot+c9ba86847ecac1751d2a@syzkaller.appspotmail.com
First crash: 22d, last: 1d08h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __tipc_sendstream / tipc_poll (2) tipc 6 2 292d 295d 0/29 auto-obsoleted due to no activity on 2025/05/25 13:47
upstream KCSAN: data-race in __tipc_sendstream / tipc_poll tipc 6 4 1448d 1463d 0/29 auto-closed as invalid on 2022/03/05 19:55

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __tipc_sendstream / tipc_poll

read-write to 0xffff888103d9bf26 of 2 bytes by task 23879 on cpu 1:
 __tipc_sendstream+0x7e1/0xb20 net/tipc/socket.c:1628
 tipc_sendstream+0x3e/0x60 net/tipc/socket.c:1546
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 sock_write_iter+0x1a7/0x1f0 net/socket.c:1195
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x52a/0x960 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2847/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103d9bf26 of 2 bytes by task 23876 on cpu 0:
 tsk_conn_cong net/tipc/socket.c:222 [inline]
 tipc_poll+0x1f9/0x350 net/tipc/socket.c:806
 sock_poll+0x20d/0x230 net/socket.c:1443
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1ee/0xb70 io_uring/poll.c:581
 io_poll_add+0x69/0xe0 io_uring/poll.c:899
 __io_issue_sqe+0xfe/0x2e0 io_uring/io_uring.c:1793
 io_issue_sqe+0x56/0xa80 io_uring/io_uring.c:1816
 io_queue_sqe io_uring/io_uring.c:2043 [inline]
 io_submit_sqe io_uring/io_uring.c:2321 [inline]
 io_submit_sqes+0x78b/0x11b0 io_uring/io_uring.c:2435
 __do_sys_io_uring_enter io_uring/io_uring.c:3285 [inline]
 __se_sys_io_uring_enter+0x1bd/0x1a30 io_uring/io_uring.c:3224
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3224
 x64_sys_call+0x27e4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01c7 -> 0x0082

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 23876 Comm: syz.0.8087 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/16 02:06 upstream 603c05a1639f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __tipc_sendstream / tipc_poll
2025/12/31 11:10 upstream c8ebd433459b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __tipc_sendstream / tipc_poll
2025/12/29 14:44 upstream 7839932417dd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __tipc_sendstream / tipc_poll
2025/12/26 09:05 upstream ccd1cdca5cd4 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __tipc_sendstream / tipc_poll
* Struck through repros no longer work on HEAD.