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Date: Wed, 4 Oct 2023 14:48:54 +0200
From: Simon Horman <horms@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org, eric.dumazet@gmail.com,
	syzbot <syzkaller@googlegroups.com>
Subject: Re: [PATCH net] netlink: annotate data-races around sk->sk_err
Message-ID: <ZR1fNgXLy9w/GnIE@kernel.org>
References: <20231003183455.3410550-1-edumazet@google.com>
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On Tue, Oct 03, 2023 at 06:34:55PM +0000, Eric Dumazet wrote:
> syzbot caught another data-race in netlink when
> setting sk->sk_err.
> 
> Annotate all of them for good measure.
> 
> BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg
> 
> write to 0xffff8881613bb220 of 4 bytes by task 28147 on cpu 0:
> netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994
> sock_recvmsg_nosec net/socket.c:1027 [inline]
> sock_recvmsg net/socket.c:1049 [inline]
> __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229
> __do_sys_recvfrom net/socket.c:2247 [inline]
> __se_sys_recvfrom net/socket.c:2243 [inline]
> __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243
> 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 0xffff8881613bb220 of 4 bytes by task 28146 on cpu 1:
> netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994
> sock_recvmsg_nosec net/socket.c:1027 [inline]
> sock_recvmsg net/socket.c:1049 [inline]
> __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229
> __do_sys_recvfrom net/socket.c:2247 [inline]
> __se_sys_recvfrom net/socket.c:2243 [inline]
> __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243
> 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: 0x00000000 -> 0x00000016
> 
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 1 PID: 28146 Comm: syz-executor.0 Not tainted 6.6.0-rc3-syzkaller-00055-g9ed22ae6be81 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>

Reviewed-by: Simon Horman <horms@kernel.org>