[PATCH 6.6 088/301] net: gro: add flush check in udp_gro_receive_segment

Greg Kroah-Hartman
2024-05-14T11:06:22Z

From: Richard Gobert <richardbgobert@gmail.com>

[ Upstream commit 5babae777c61aa8a8679d59d3cdc54165ad96d42 ]

GRO-GSO path is supposed to be transparent and as such L3 flush checks are
relevant to all UDP flows merging in GRO. This patch uses the same logic
and code from tcp_gro_receive, terminating merge if flush is non zero.

Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.")
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/udp_offload.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 889d4926fc0c1..e5971890d637d 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -471,6 +471,7 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
struct sk_buff *p;
unsigned int ulen;
int ret = 0;
+ int flush;

/* requires non zero csum, for symmetry with GSO */
if (!uh->check) {
@@ -504,13 +505,22 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
return p;
}

+ flush = NAPI_GRO_CB(p)->flush;
+
+ if (NAPI_GRO_CB(p)->flush_id != 1 ||
+ NAPI_GRO_CB(p)->count != 1 ||
+ !NAPI_GRO_CB(p)->is_atomic)
+ flush |= NAPI_GRO_CB(p)->flush_id;
+ else
+ NAPI_GRO_CB(p)->is_atomic = false;
+
/* Terminate the flow on len mismatch or if it grow "too much".
* Under small packet flood GRO count could elsewhere grow a lot
* leading to excessive truesize values.
* On len mismatch merge the first packet shorter than gso_size,
* otherwise complete the GRO packet.
*/
- if (ulen > ntohs(uh2->len)) {
+ if (ulen > ntohs(uh2->len) || flush) {
pp = p;
} else {
if (NAPI_GRO_CB(skb)->is_flist) {
--
2.43.0