From d94d95ae0dd0086f465442fad48fbb2fa1bd7ed3 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 13 Apr 2021 05:41:35 -0700 Subject: gro: ensure frag0 meets IP header alignment commit 38ec4944b593fd90c5ef42aaaa53e66ae5769d04 upstream. 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 Reported-by: Guenter Roeck Cc: Xuan Zhuo Cc: "Michael S. Tsirkin" Cc: Jason Wang Acked-by: Michael S. Tsirkin Tested-by: Guenter Roeck Signed-off-by: David S. Miller Signed-off-by: Matthieu Baerts Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 06176ef2a842..5f2e6451ece5 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2788,6 +2788,15 @@ static inline void skb_propagate_pfmemalloc(struct page *page, skb->pfmemalloc = true; } +/** + * skb_frag_off() - Returns the offset of a skb fragment + * @frag: the paged fragment + */ +static inline unsigned int skb_frag_off(const skb_frag_t *frag) +{ + return frag->page_offset; +} + /** * skb_frag_page - retrieve the page referred to by a paged fragment * @frag: the paged fragment -- cgit v1.2.3