bpf: sockmap, consume_skb in close path

commit 7ebc14d507b4b55105da8d1a1eda323381529cc7 upstream.

Currently, when a sock is closed and the bpf_tcp_close() callback is
used we remove memory but do not free the skb. Call consume_skb() if
the skb is attached to the buffer.

Reported-by: syzbot+d464d2c20c717ef5a6a8@syzkaller.appspotmail.com
Fixes: 1aa12bdf1bfb ("bpf: sockmap, add sock close() hook to remove socks")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 12b25ed4bf20e148ca06bd6f17e22adf3dea0e83..fc7ee4357381bbc2341b0d42c0373b0320ce2513 100644 (file)
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -471,7 +471,8 @@ static int free_sg(struct sock *sk, int start, struct sk_msg_buff *md)
        while (sg[i].length) {
                free += sg[i].length;
                sk_mem_uncharge(sk, sg[i].length);
-               put_page(sg_page(&sg[i]));
+               if (!md->skb)
+                       put_page(sg_page(&sg[i]));
                sg[i].length = 0;
                sg[i].page_link = 0;
                sg[i].offset = 0;
@@ -480,6 +481,8 @@ static int free_sg(struct sock *sk, int start, struct sk_msg_buff *md)
                if (i == MAX_SKB_FRAGS)
                        i = 0;
        }
+       if (md->skb)
+               consume_skb(md->skb);
 
        return free;
 }