From: Eric Dumazet <edumazet@google.com>
Date: Thu, 31 Aug 2023 21:38:12 +0000 (+0000)
Subject: gve: fix frag_list chaining
X-Git-Tag: v6.6-rc1~29^2~26
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=817c7cd2043a83a3d8147f40eea1505ac7300b62;p=thirdparty%2Fkernel%2Flinux.git

gve: fix frag_list chaining

gve_rx_append_frags() is able to build skbs chained with frag_list,
like GRO engine.

Problem is that shinfo->frag_list should only be used
for the head of the chain.

All other links should use skb->next pointer.

Otherwise, built skbs are not valid and can cause crashes.

Equivalent code in GRO (skb_gro_receive()) is:

    if (NAPI_GRO_CB(p)->last == p)
        skb_shinfo(p)->frag_list = skb;
    else
        NAPI_GRO_CB(p)->last->next = skb;
    NAPI_GRO_CB(p)->last = skb;

Fixes: 9b8dd5e5ea48 ("gve: DQO: Add RX path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Bailey Forrest <bcf@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Catherine Sullivan <csully@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/ethernet/google/gve/gve_rx_dqo.c b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
index ea0e38b4d9e9f..f281e42a7ef96 100644
--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -570,7 +570,10 @@ static int gve_rx_append_frags(struct napi_struct *napi,
 		if (!skb)
 			return -1;
 
-		skb_shinfo(rx->ctx.skb_tail)->frag_list = skb;
+		if (rx->ctx.skb_tail == rx->ctx.skb_head)
+			skb_shinfo(rx->ctx.skb_head)->frag_list = skb;
+		else
+			rx->ctx.skb_tail->next = skb;
 		rx->ctx.skb_tail = skb;
 		num_frags = 0;
 	}