| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 140/151] net: udp: fix UDP header access on Fast/frag0 UDP GRO | Date | Tue, 17 Nov 2020 14:06:10 +0100 |
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From: Alexander Lobakin <alobakin@pm.me>
[ Upstream commit 4b1a86281cc1d0de46df3ad2cb8c1f86ac07681c ]
UDP GRO uses udp_hdr(skb) in its .gro_receive() callback. While it's probably OK for non-frag0 paths (when all headers or even the entire frame are already in skb head), this inline points to junk when using Fast GRO (napi_gro_frags() or napi_gro_receive() with only Ethernet header in skb head and all the rest in the frags) and breaks GRO packet compilation and the packet flow itself. To support both modes, skb_gro_header_fast() + skb_gro_header_slow() are typically used. UDP even has an inline helper that makes use of them, udp_gro_udphdr(). Use that instead of troublemaking udp_hdr() to get rid of the out-of-order delivers.
Present since the introduction of plain UDP GRO in 5.0-rc1.
Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.") Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Alexander Lobakin <alobakin@pm.me> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/udp_offload.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -349,7 +349,7 @@ out: static struct sk_buff *udp_gro_receive_segment(struct list_head *head, struct sk_buff *skb) { - struct udphdr *uh = udp_hdr(skb); + struct udphdr *uh = udp_gro_udphdr(skb); struct sk_buff *pp = NULL; struct udphdr *uh2; struct sk_buff *p;
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