Patch "gro: Enter slow-path if there is no tailroom" has been added to the 4.9-stable tree

Patch "gro: Enter slow-path if there is no tailroom" has been added to the 4.9-stable tree

[gregkh]

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

    gro: Enter slow-path if there is no tailroom

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:
     gro-enter-slow-path-if-there-is-no-tailroom.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 Jan 12 21:37:26 CET 2017
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 10 Jan 2017 12:24:01 -0800
Subject: gro: Enter slow-path if there is no tailroom

From: Herbert Xu <herbert@gondor.apana.org.au>


[ Upstream commit 1272ce87fa017ca4cf32920764d879656b7a005a ]

The GRO path has a fast-path where we avoid calling pskb_may_pull
and pskb_expand by directly accessing frag0.  However, this should
only be done if we have enough tailroom in the skb as otherwise
we'll have to expand it later anyway.

This patch adds the check by capping frag0_len with the skb tailroom.

Fixes: cb18978cbf45 ("gro: Open-code final pskb_may_pull")
Reported-by: Slava Shwartsman <slavash@mellanox.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/dev.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4453,7 +4453,8 @@ static void skb_gro_reset_offset(struct
 	    pinfo->nr_frags &&
 	    !PageHighMem(skb_frag_page(frag0))) {
 		NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
-		NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(frag0);
+		NAPI_GRO_CB(skb)->frag0_len = min(skb_frag_size(frag0),
+						  skb->end - skb->tail);
 	}
 }
 


Patches currently in stable-queue which might be from herbert@gondor.apana.org.au are

queue-4.9/gro-disable-frag0-optimization-on-ipv6-ext-headers.patch
queue-4.9/gro-enter-slow-path-if-there-is-no-tailroom.patch