Patch "net: adjust skb->truesize in ___pskb_trim()" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    net: adjust skb->truesize in ___pskb_trim()

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-adjust-skb-truesize-in-___pskb_trim.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu May 11 11:08:24 CEST 2017
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 26 Apr 2017 09:07:46 -0700
Subject: net: adjust skb->truesize in ___pskb_trim()

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit c21b48cc1bbf2f5af3ef54ada559f7fadf8b508b ]

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 <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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/skbuff.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1572,6 +1572,8 @@ done:
 		skb_set_tail_pointer(skb, len);
 	}
 
+	if (!skb->sk || skb->destructor == sock_edemux)
+		skb_condense(skb);
 	return 0;
 }
 EXPORT_SYMBOL(___pskb_trim);


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.9/net-adjust-skb-truesize-in-___pskb_trim.patch
queue-4.9/tcp-do-not-underestimate-skb-truesize-in-tcp_trim_head.patch
queue-4.9/tcp-fix-wraparound-issue-in-tcp_lp.patch
queue-4.9/tcp-do-not-inherit-fastopen_req-from-parent.patch