net/unix: fix logic about sk_peek_offset

Now send with MSG_PEEK can return data from multiple SKBs.

Unfortunately we take into account the peek offset for each skb,
that is wrong. We need to apply the peek offset only once.

In addition, the peek offset should be used only if MSG_PEEK is set.

Cc: "David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING
Cc: Eric Dumazet <edumazet@google.com> (commit_signer:1/14=7%)
Cc: Aaron Conole <aconole@bytheb.org>
Fixes: 9f389e35674f ("af_unix: return data from multiple SKBs on recv() with MSG_PEEK flag")
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Tested-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index ef31b40ad55000a5fd029d7479b546483cc782b3..94f658235fb49a0c644a84867302cc00a75243d5 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2064,6 +2064,11 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state)
                goto out;
        }
 
+       if (flags & MSG_PEEK)
+               skip = sk_peek_offset(sk, flags);
+       else
+               skip = 0;
+
        do {
                int chunk;
                struct sk_buff *skb, *last;
@@ -2112,7 +2117,6 @@ unlock:
                        break;
                }
 
-               skip = sk_peek_offset(sk, flags);
                while (skip >= unix_skb_len(skb)) {
                        skip -= unix_skb_len(skb);
                        last = skb;
@@ -2179,14 +2183,12 @@ unlock:
                        if (UNIXCB(skb).fp)
                                scm.fp = scm_fp_dup(UNIXCB(skb).fp);
 
-                       if (skip) {
-                               sk_peek_offset_fwd(sk, chunk);
-                               skip -= chunk;
-                       }
+                       sk_peek_offset_fwd(sk, chunk);
 
                        if (UNIXCB(skb).fp)
                                break;
 
+                       skip = 0;
                        last = skb;
                        last_len = skb->len;
                        unix_state_lock(sk);