[moderation] [afs?] [net?] KCSAN: data-race in rxrpc_send_data / rxrpc_send_data_packet (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 765b233a9b94 Merge tag 'i2c-for-6.19-rc2' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16b65392580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b319ff1b6a2797ca
dashboard link: https://syzkaller.appspot.com/bug?extid=17f64793f5ca7e8f5054
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [da...@davemloft.net dhow...@redhat.com edum...@google.com ho...@kernel.org ku...@kernel.org linu...@lists.infradead.org linux-...@vger.kernel.org marc....@auristor.com net...@vger.kernel.org pab...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d64794bf10fb/disk-765b233a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c2e3d58023b4/vmlinux-765b233a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d2f3b3bb88ec/bzImage-765b233a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17f647...@syzkaller.appspotmail.com

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

write to 0xffff888104f59000 of 8 bytes by task 11824 on cpu 0:
rxrpc_alloc_txqueue net/rxrpc/sendmsg.c:-1 [inline]
rxrpc_send_data+0x8c5/0x1560 net/rxrpc/sendmsg.c:398
rxrpc_do_sendmsg+0xc16/0xcc0 net/rxrpc/sendmsg.c:771
rxrpc_sendmsg+0x47c/0x590 net/rxrpc/af_rxrpc.c:598
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x145/0x180 net/socket.c:742
____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592
___sys_sendmsg+0x17b/0x1d0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47
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 0xffff888104f59000 of 8 bytes by task 11826 on cpu 1:
rxrpc_prepare_data_packet net/rxrpc/output.c:566 [inline]
rxrpc_send_data_packet+0x465/0x1df0 net/rxrpc/output.c:664
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+0x149/0x290 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000000000000 -> 0xffff888104f5c800

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11826 Comm: krxrpcio/0 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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