The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 38ec4944b593fd90c5ef42aaaa53e66ae5769d04 Mon Sep 17 00:00:00 2001
From: Eric Dumazet edumazet@google.com Date: Tue, 13 Apr 2021 05:41:35 -0700 Subject: [PATCH] gro: ensure frag0 meets IP header alignment
After commit 0f6925b3e8da ("virtio_net: Do not pull payload in skb->head") Guenter Roeck reported one failure in his tests using sh architecture.
After much debugging, we have been able to spot silent unaligned accesses in inet_gro_receive()
The issue at hand is that upper networking stacks assume their header is word-aligned. Low level drivers are supposed to reserve NET_IP_ALIGN bytes before the Ethernet header to make that happen.
This patch hardens skb_gro_reset_offset() to not allow frag0 fast-path if the fragment is not properly aligned.
Some arches like x86, arm64 and powerpc do not care and define NET_IP_ALIGN as 0, this extra check will be a NOP for them.
Note that if frag0 is not used, GRO will call pskb_may_pull() as many times as needed to pull network and transport headers.
Fixes: 0f6925b3e8da ("virtio_net: Do not pull payload in skb->head") Fixes: 78a478d0efd9 ("gro: Inline skb_gro_header and cache frag0 virtual address") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: Guenter Roeck linux@roeck-us.net Cc: Xuan Zhuo xuanzhuo@linux.alibaba.com Cc: "Michael S. Tsirkin" mst@redhat.com Cc: Jason Wang jasowang@redhat.com Acked-by: Michael S. Tsirkin mst@redhat.com Tested-by: Guenter Roeck linux@roeck-us.net Signed-off-by: David S. Miller davem@davemloft.net
diff --git a/net/core/dev.c b/net/core/dev.c index af8c1ea040b9..1f79b9aa9a3f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5924,7 +5924,8 @@ static void skb_gro_reset_offset(struct sk_buff *skb) NAPI_GRO_CB(skb)->frag0_len = 0;
if (!skb_headlen(skb) && pinfo->nr_frags && - !PageHighMem(skb_frag_page(frag0))) { + !PageHighMem(skb_frag_page(frag0)) && + (!NET_IP_ALIGN || !(skb_frag_off(frag0) & 3))) { NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0); NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int, skb_frag_size(frag0),