Commit c21b48cc authored Apr 26, 2017 by Eric Dumazet Committed by David S. Miller Apr 28, 2017

net: adjust skb->truesize in ___pskb_trim()



Andrey found a way to trigger the WARN_ON_ONCE(delta < len) in
skb_try_coalesce() using syzkaller and a filter attached to a TCP
socket.

As we did recently in commit 158f323b ("net: adjust skb->truesize in
pskb_expand_head()") we can adjust skb->truesize from ___pskb_trim(),
via a call to skb_condense().

If all frags were freed, then skb->truesize can be recomputed.

This call can be done if skb is not yet owned, or destructor is
sock_edemux().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 7162fb24

net/core/skbuff.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1576,6 +1576,8 @@ done:
		skb_set_tail_pointer(skb, len);
		}

		if (!skb->sk \|\| skb->destructor == sock_edemux)
		skb_condense(skb);
		return 0;
		}
		EXPORT_SYMBOL(___pskb_trim);

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