From c21b48cc1bbf2f5af3ef54ada559f7fadf8b508b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 26 Apr 2017 09:07:46 -0700 Subject: [PATCH] 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 158f323b9868 ("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 Reported-by: Andrey Konovalov Cc: Willem de Bruijn Signed-off-by: David S. Miller --- net/core/skbuff.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f86bf69cfb8d..f1d04592ace0 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -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); -- 2.30.2