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af_unix: Call manage_oob() for every skb in unix_stream_read_generic().

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When we call recv() for AF_UNIX socket, we first peek one skb and
calls manage_oob() to check if the skb is sent with MSG_OOB.

However, when we fetch the next (and the following) skb, manage_oob()
is not called now, leading a wrong behaviour.

Let's say a socket send()s "hello" with MSG_OOB and the peer tries
to recv() 5 bytes with MSG_PEEK.  Here, we should get only "hell"
without 'o', but actually not:

  >>> from socket import *
  >>> c1, c2 = socketpair(AF_UNIX, SOCK_STREAM)
  >>> c1.send(b'hello', MSG_OOB)
  5
  >>> c2.recv(5, MSG_PEEK)
  b'hello'

The first skb fills 4 bytes, and the next skb is peeked but not
properly checked by manage_oob().

Let's move up the again label to call manage_oob() for evry skb.

With this patch:

  >>> from socket import *
  >>> c1, c2 = socketpair(AF_UNIX, SOCK_STREAM)
  >>> c1.send(b'hello', MSG_OOB)
  5
  >>> c2.recv(5, MSG_PEEK)
  b'hell'

Fixes: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240410171016.7621-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2024-04-10 10:10:15 -07:00 committed by Jakub Kicinski
parent 90be7a5ce0
commit 283454c8a1
1 changed files with 1 additions and 1 deletions
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2
net/unix/af_unix.c
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@ -2741,6 +2741,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state,
last = skb = skb_peek(&sk->sk_receive_queue);
last_len = last ? last->len : 0;
again:
#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
if (skb) {
skb = manage_oob(skb, sk, flags, copied);
@ -2752,7 +2753,6 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state,
}
}
#endif
again:
if (skb == NULL) {
if (copied >= target)
goto unlock;