gro: Enter slow-path if there is no tailroom

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: cb18978 ("gro: Open-code final pskb_may_pull") Reported-by: Slava Shwartsman <[email protected]> Signed-off-by: Herbert Xu <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
zhenyw · Jan 11, 2017 · 1272ce8 · 1272ce8
1 parent 9f9b74e
commit 1272ce8
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/net/core/dev.c b/net/core/dev.c
@@ -4441,7 +4441,8 @@ static void skb_gro_reset_offset(struct sk_buff *skb)
 	    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);
 	}
 }