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BUG: KCSAN: data-race in isotp_sendmsg / isotp_sendmsg

read to 0xffff8881446724b4 of 4 bytes by task 15977 on cpu 1:
 isotp_sendmsg+0x213/0xc90 net/can/isotp.c:957
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2558
 ___sys_sendmsg net/socket.c:2612 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2641
 __do_sys_sendmsg net/socket.c:2650 [inline]
 __se_sys_sendmsg net/socket.c:2648 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881446724b4 of 4 bytes by task 16000 on cpu 0:
 isotp_sendmsg+0x432/0xc90 net/can/isotp.c:1123
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2558
 ___sys_sendmsg net/socket.c:2612 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2698
 __do_sys_sendmmsg net/socket.c:2727 [inline]
 __se_sys_sendmmsg net/socket.c:2724 [inline]
 __x64_sys_sendmmsg+0x57/0x60 net/socket.c:2724
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000004 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16000 Comm: syz-executor.2 Not tainted 6.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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