From 29e98242783ed3ba569797846a606ba66f781625 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 16 May 2014 11:34:37 -0700 Subject: [PATCH] net: gro: make sure skb->cb[] initial content has not to be zero MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Starting from linux-3.13, GRO attempts to build full size skbs. Problem is the commit assumed one particular field in skb->cb[] was clean, but it is not the case on some stacked devices. Timo reported a crash in case traffic is decrypted before reaching a GRE device. Fix this by initializing NAPI_GRO_CB(skb)->last at the right place, this also removes one conditional. Thanks a lot to Timo for providing full reports and bisecting this. Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb") Bisected-by: Timo Teras Signed-off-by: Eric Dumazet Tested-by: Timo Teräs Signed-off-by: David S. Miller --- net/core/dev.c | 1 + net/core/skbuff.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 6da649b..ed928e8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3951,6 +3951,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff } NAPI_GRO_CB(skb)->count = 1; NAPI_GRO_CB(skb)->age = jiffies; + NAPI_GRO_CB(skb)->last = skb; skb_shinfo(skb)->gso_size = skb_gro_len(skb); skb->next = napi->gro_list; napi->gro_list = skb; diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1b62343..8383b2b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3076,7 +3076,7 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) if (unlikely(p->len + len >= 65536)) return -E2BIG; - lp = NAPI_GRO_CB(p)->last ?: p; + lp = NAPI_GRO_CB(p)->last; pinfo = skb_shinfo(lp); if (headlen <= offset) { @@ -3192,7 +3192,7 @@ merge: __skb_pull(skb, offset); - if (!NAPI_GRO_CB(p)->last) + if (NAPI_GRO_CB(p)->last == p) skb_shinfo(p)->frag_list = skb; else NAPI_GRO_CB(p)->last->next = skb; -- 2.7.4