4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: Daniel Borkmann <dan...@iogearbox.net> commit 5121700b346b6160ccc9411194e3f1f417c340d1 upstream. While working on bpf_tcp_sendmsg() code, I noticed that when a sk->sk_err is set we error out with err = sk->sk_err. However this is problematic since sk->sk_err is a positive error value and therefore we will neither go into sk_stream_error() nor will we report an error back to user space. I had this case with EPIPE and user space was thinking sendmsg() succeeded since EPIPE is a positive value, thinking we submitted 32 bytes. Fix it by negating the sk->sk_err value. Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data") Signed-off-by: Daniel Borkmann <dan...@iogearbox.net> Acked-by: John Fastabend <john.fastab...@gmail.com> Signed-off-by: Alexei Starovoitov <a...@kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- kernel/bpf/sockmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -952,7 +952,7 @@ static int bpf_tcp_sendmsg(struct sock * int copy; if (sk->sk_err) { - err = sk->sk_err; + err = -sk->sk_err; goto out_err; }