netdev - [PATCH net] net/tls: avoid NULL pointer deref on nskb->sk in fallback

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Date:   Mon, 29 Apr 2019 12:19:12 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        borisp@...lanox.com, aviadye@...lanox.com, davejwatson@...com,
        john.fastabend@...il.com, daniel@...earbox.net,
        alexei.starovoitov@...il.com, saeedm@...lanox.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Simon Horman <simon.horman@...ronome.com>
Subject: [PATCH net] net/tls: avoid NULL pointer deref on nskb->sk in fallback

update_chksum() accesses nskb->sk before it has been set
by complete_skb(), move the init up.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Simon Horman <simon.horman@...ronome.com>
---
 net/tls/tls_device_fallback.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tls/tls_device_fallback.c b/net/tls/tls_device_fallback.c
index a3ebd4b02714..c3a5fe624b4e 100644
--- a/net/tls/tls_device_fallback.c
+++ b/net/tls/tls_device_fallback.c
@@ -201,13 +201,14 @@ static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
 
 	skb_put(nskb, skb->len);
 	memcpy(nskb->data, skb->data, headln);
-	update_chksum(nskb, headln);
 
 	nskb->destructor = skb->destructor;
 	nskb->sk = sk;
 	skb->destructor = NULL;
 	skb->sk = NULL;
 
+	update_chksum(nskb, headln);
+
 	delta = nskb->truesize - skb->truesize;
 	if (likely(delta < 0))
 		WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
-- 
2.21.0