linux-kernel - [PATCH 4.19 044/170] ipv6: frags: Fix bogus skb->sk in reassembled packets

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Date:   Mon,  7 Jan 2019 13:31:11 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xiumei Mu <xmu@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.19 044/170] ipv6: frags: Fix bogus skb->sk in reassembled packets

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@...dor.apana.org.au>

[ Upstream commit d15f5ac8deea936d3adf629421a66a88b42b8a2f ]

It was reported that IPsec would crash when it encounters an IPv6
reassembled packet because skb->sk is non-zero and not a valid
pointer.

This is because skb->sk is now a union with ip_defrag_offset.

This patch fixes this by resetting skb->sk when exiting from
the reassembly code.

Reported-by: Xiumei Mu <xmu@...hat.com>
Fixes: 219badfaade9 ("ipv6: frags: get rid of ip6frag_skb_cb/...")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv6/reassembly.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -384,6 +384,7 @@ static int ip6_frag_reasm(struct frag_qu
 		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
 			kfree_skb_partial(fp, headstolen);
 		} else {
+			fp->sk = NULL;
 			if (!skb_shinfo(head)->frag_list)
 				skb_shinfo(head)->frag_list = fp;
 			head->data_len += fp->len;