[14/26] ipv6: fix possible crashes in ip6_cork_release()

[Ben Hutchings]

3.2.48-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 284041ef21fdf2e0d216ab6b787bc9072b4eb58a ]

commit 0178b695fd6b4 ("ipv6: Copy cork options in ip6_append_data")
added some code duplication and bad error recovery, leading to potential
crash in ip6_cork_release() as kfree() could be called with garbage.

use kzalloc() to make sure this wont happen.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/ipv6/ip6_output.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3ccd9b2..6aadaa8 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1233,7 +1233,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
 			if (WARN_ON(np->cork.opt))
 				return -EINVAL;
 
-			np->cork.opt = kmalloc(opt->tot_len, sk->sk_allocation);
+			np->cork.opt = kzalloc(opt->tot_len, sk->sk_allocation);
 			if (unlikely(np->cork.opt == NULL))
 				return -ENOBUFS;
 

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