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70a36f5713
syzbot/KCSAN complained about UDP_ENCAP_L2TPINUDP setsockopt() racing. Add READ_ONCE()/WRITE_ONCE() to document races on this lockless field. syzbot report was: BUG: KCSAN: data-race in udp_lib_setsockopt / udp_lib_setsockopt read-write to 0xffff8881083603fa of 1 bytes by task 16557 on cpu 0: udp_lib_setsockopt+0x682/0x6c0 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2779 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 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 read-write to 0xffff8881083603fa of 1 bytes by task 16554 on cpu 1: udp_lib_setsockopt+0x682/0x6c0 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2779 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 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: 0x01 -> 0x05 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 16554 Comm: syz-executor.5 Not tainted 6.5.0-rc7-syzkaller-00004-gf7757129e3de #0 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.