netdev - [PATCH] ipv6: raw: Deduct extension header length in rawv6_push_pending

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Message-ID: <Y7y4Wsfjm0G7kUBm@gondor.apana.org.au>
Date:   Tue, 10 Jan 2023 08:59:06 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Kyle Zeng <zengyhkyle@...il.com>, Jakub Kicinski <kuba@...nel.org>,
        davem@...emloft.net, yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org
Subject: [PATCH] ipv6: raw: Deduct extension header length in
 rawv6_push_pending_frames

On Mon, Jan 09, 2023 at 11:08:08AM +0100, Eric Dumazet wrote:
>
> Kyle posted one in https://lore.kernel.org/netdev/Y7s%2FFofVXLwoVgWt@westworld/

Thanks for the link!

It looks like I didn't think about extension headers in the original
patch.

---8<---
The total cork length created by ip6_append_data includes extension
headers, so we must exclude them when comparing them against the
IPV6_CHECKSUM offset which does not include extension headers.

Reported-by: Kyle Zeng <zengyhkyle@...il.com>
Fixes: 357b40a18b04 ("[IPV6]: IPV6_CHECKSUM socket option can corrupt kernel memory")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index c51d5ce3711c..c68020b8de89 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -539,6 +539,7 @@ static int rawv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
 				     struct raw6_sock *rp)
 {
+	struct ipv6_txoptions *opt;
 	struct sk_buff *skb;
 	int err = 0;
 	int offset;
@@ -556,6 +557,9 @@ static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
 
 	offset = rp->offset;
 	total_len = inet_sk(sk)->cork.base.length;
+	opt = inet6_sk(sk)->cork.opt;
+	total_len -= opt ? opt->opt_flen : 0;
+
 	if (offset >= total_len - 1) {
 		err = -EINVAL;
 		ip6_flush_pending_frames(sk);
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt