[PATCH bpf-next] bpf: bpf_setsockopt: reset sock dst on SO_MARK changes

[Peter Oskolkov]

In sock_setsockopt() (net/core/sock.h), when SO_MARK option is used
to change sk_mark, sk_dst_reset(sk) is called. The same should be done
in bpf_setsockopt.

Reported-by: Maciej Żenczykowski <m...@google.com>
Signed-off-by: Peter Oskolkov <p...@google.com>
---
 net/core/filter.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 2b3b436ef545..0c1bc6ccfd7f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4132,7 +4132,10 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, 
bpf_sock,
                        sk->sk_rcvlowat = val ? : 1;
                        break;
                case SO_MARK:
-                       sk->sk_mark = val;
+                       if (sk->sk_mark != val) {
+                               sk->sk_mark = val;
+                               sk_dst_reset(sk);
+                       }
                        break;
                default:
                        ret = -EINVAL;
--