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BUG: KCSAN: data-race in fib_table_lookup / fib_table_lookup

write to 0xffff888112e1ca62 of 1 bytes by task 22194 on cpu 1:
 fib_alias_accessed net/ipv4/fib_lookup.h:32 [inline]
 fib_table_lookup+0x355/0xd50 net/ipv4/fib_trie.c:1591
 fib_lookup include/net/ip_fib.h:385 [inline]
 ip_route_output_key_hash_rcu+0x3a1/0x12d0 net/ipv4/route.c:2752
 ip_route_output_key_hash net/ipv4/route.c:2642 [inline]
 __ip_route_output_key include/net/route.h:131 [inline]
 ip_route_output_flow+0xa6/0x160 net/ipv4/route.c:2870
 udp_sendmsg+0xe80/0x1310 net/ipv4/udp.c:1221
 udpv6_sendmsg+0x76d/0x1550 net/ipv6/udp.c:1388
 inet6_sendmsg+0xaf/0xd0 net/ipv6/af_inet6.c:661
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x8b/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2750
 x64_sys_call+0x2be5/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888112e1ca62 of 1 bytes by task 22195 on cpu 0:
 fib_alias_accessed net/ipv4/fib_lookup.h:31 [inline]
 fib_table_lookup+0x32c/0xd50 net/ipv4/fib_trie.c:1591
 fib_lookup include/net/ip_fib.h:385 [inline]
 ip_route_output_key_hash_rcu+0x3a1/0x12d0 net/ipv4/route.c:2752
 ip_route_output_key_hash net/ipv4/route.c:2642 [inline]
 __ip_route_output_key include/net/route.h:131 [inline]
 ip_route_output_flow+0xa6/0x160 net/ipv4/route.c:2870
 udp_sendmsg+0xe80/0x1310 net/ipv4/udp.c:1221
 udpv6_sendmsg+0x76d/0x1550 net/ipv6/udp.c:1388
 inet6_sendmsg+0xaf/0xd0 net/ipv6/af_inet6.c:661
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x8b/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2750
 x64_sys_call+0x2be5/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22195 Comm: syz-executor.0 Not tainted 6.9.0-rc4-syzkaller-00031-g96fca68c4fbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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