syzbot

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BUG: KCSAN: data-race in packet_recvmsg / packet_recvmsg

read-write to 0xffff888129f75028 of 2 bytes by task 27860 on cpu 0:
 packet_recvmsg+0x557/0xc80 net/packet/af_packet.c:3480
 sock_recvmsg_nosec+0x104/0x130 net/socket.c:1078
 ____sys_recvmsg+0x26f/0x280 net/socket.c:2848
 ___sys_recvmsg+0x11f/0x370 net/socket.c:2892
 do_recvmmsg+0x1ef/0x540 net/socket.c:2987
 __sys_recvmmsg net/socket.c:3061 [inline]
 __do_sys_recvmmsg net/socket.c:3084 [inline]
 __se_sys_recvmmsg net/socket.c:3077 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3077
 x64_sys_call+0x27aa/0x3000 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888129f75028 of 18 bytes by task 27858 on cpu 1:
 packet_recvmsg+0x775/0xc80 net/packet/af_packet.c:3516
 sock_recvmsg_nosec+0x104/0x130 net/socket.c:1078
 ____sys_recvmsg+0x26f/0x280 net/socket.c:2848
 ___sys_recvmsg+0x11f/0x370 net/socket.c:2892
 do_recvmmsg+0x1ef/0x540 net/socket.c:2987
 __sys_recvmmsg net/socket.c:3061 [inline]
 __do_sys_recvmmsg net/socket.c:3084 [inline]
 __se_sys_recvmmsg net/socket.c:3077 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3077
 x64_sys_call+0x27aa/0x3000 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27858 Comm: syz.3.8265 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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