KCSAN: data-race in rds_sendmsg / rds_sendmsg (3)

Status: auto-obsoleted due to no activity on 2026/09/08 17:09
Subsystems: rds
Labels: race:benign prio:low
[Documentation on labels]
Reported-by: syzbot+879c1877016972360186@syzkaller.appspotmail.com
First crash: 70d, last: 70d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
bc29e69e assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in rds_sendmsg / rds_sendmsg (3) 2026/07/16 00:02 2026/07/16 00:02 2026/07/16 01:05 10d97020
13020ee4 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in rds_sendmsg / rds_sendmsg (3) 2026/07/14 17:09 2026/07/14 17:09 2026/07/14 17:34 2130f682
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
[PATCH net-next v5 08/12] net/rds: hold connection references in lookup, sockets and c_passive 2 (2) 2026/09/23 07:11
[PATCH net-next v6 08/12] net/rds: hold connection references in lookup, sockets and c_passive 1 (1) 2026/09/22 08:54
[PATCH net-next v4 08/12] net/rds: hold connection references in lookup, sockets and c_passive 2 (2) 2026/09/21 09:15
[PATCH net-next v3 08/13] net/rds: hold connection references in lookup, sockets and c_passive 2 (2) 2026/09/17 09:38
[PATCH net-next v2 6/9] net/rds: hold connection references in lookup, sockets and c_passive 2 (2) 2026/09/16 04:36
[PATCH net-next 3/6] net/rds: hold connection references in lookup, sockets and c_passive 2 (2) 2026/09/10 01:03
[syzbot] [rds?] KCSAN: data-race in rds_sendmsg / rds_sendmsg (3) 0 (1) 2026/07/16 16:50
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in rds_sendmsg / rds_sendmsg rds 6 4 1021d 1071d 0/29 auto-obsoleted due to no activity on 2024/01/11 06:36
upstream KCSAN: data-race in rds_sendmsg / rds_sendmsg (2) rds 6 1 636d 636d 0/29 auto-obsoleted due to no activity on 2025/02/19 22:31

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

write to 0xffff888101dec818 of 8 bytes by task 30904 on cpu 0:
 rds_sendmsg+0xc1f/0x1580 net/rds/send.c:1332
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x532/0x580 net/socket.c:2684
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2773
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888101dec818 of 8 bytes by task 30905 on cpu 1:
 rds_sendmsg+0xc1f/0x1580 net/rds/send.c:1332
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x532/0x580 net/socket.c:2684
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2773
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88811b61faf0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 30905 Comm: syz.5.5733 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================
atomic_op ffff888118e74d28 conn xmit_atomic 0000000000000000

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/14 17:09 upstream 3b029c035b34 2130f682 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in rds_sendmsg / rds_sendmsg
* Struck through repros no longer work on HEAD.