| Message ID | 20210413124136.2750358-1-eric.dumazet@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net] gro: ensure frag0 meets IP header alignment | expand |
On Tue, Apr 13, 2021 at 05:41:35AM -0700, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > 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> Seems to make sense. Acked-by: Michael S. Tsirkin <mst@redhat.com> > --- > net/core/dev.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/net/core/dev.c b/net/core/dev.c > index af8c1ea040b9364b076e2d72f04dc3de2d7e2f11..1f79b9aa9a3f2392fddd1401f95ad098b5e03204 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), > -- > 2.31.1.295.g9ea45b61b8-goog
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Tue, 13 Apr 2021 05:41:35 -0700 you wrote: > From: Eric Dumazet <edumazet@google.com> > > 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() > > [...] Here is the summary with links: - [net] gro: ensure frag0 meets IP header alignment https://git.kernel.org/netdev/net/c/38ec4944b593 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/net/core/dev.c b/net/core/dev.c index af8c1ea040b9364b076e2d72f04dc3de2d7e2f11..1f79b9aa9a3f2392fddd1401f95ad098b5e03204 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),