netdev - [PATCH net 1/2] ipv6: ping: fix wrong checksum for large frames

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Message-Id: <20221011212729.3777710-2-eric.dumazet@gmail.com>
Date:   Tue, 11 Oct 2022 14:27:28 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Maciej Żenczykowski <maze@...gle.com>,
        Pavel Begunkov <asml.silence@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Lorenzo Colitti <lorenzo@...gle.com>
Subject: [PATCH net 1/2] ipv6: ping: fix wrong checksum for large frames

From: Eric Dumazet <edumazet@...gle.com>

For a given ping datagram, ping_getfrag() is called once
per skb fragment.

A large datagram requiring more than one page fragment
is currently getting the checksum of the last fragment,
instead of the cumulative one.

After this patch, "ping -s 35000 ::1" is working correctly.

Fixes: 6d0bfe226116 ("net: ipv6: Add IPv6 support to the ping socket.")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Lorenzo Colitti <lorenzo@...gle.com>
Cc: Maciej Żenczykowski <maze@...gle.com>
---
 net/ipv4/ping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 517042caf6dc10c46f6ddb349d99789e4f072382..705672f319e16645d5fe2f333ed00dbd020e1ea2 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -639,7 +639,7 @@ int ping_getfrag(void *from, char *to,
 	 * wcheck, it will be finalized in ping_v4_push_pending_frames.
 	 */
 	if (pfh->family == AF_INET6) {
-		skb->csum = pfh->wcheck;
+		skb->csum = csum_block_add(skb->csum, pfh->wcheck, odd);
 		skb->ip_summed = CHECKSUM_NONE;
 		pfh->wcheck = 0;
 	}
-- 
2.38.0.rc1.362.ged0d419d3c-goog