ah6: fix error return code in ah6_input()

stable inclusion
from linux-4.19.160
commit f8c18eab5413d1edbfdeda8e8102780c5af8c64d

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

[ Upstream commit a5ebcbdf ]

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NZhang Changzhong <zhangchangzhong@huawei.com>
Link: https://lore.kernel.org/r/1605581105-35295-1-git-send-email-zhangchangzhong@huawei.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NAichun Li <liaichun@huawei.com>
Reviewed-by: Nwangxiaopeng <wangxiaopeng7@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

net/ipv6/ah6.c

@@ -600,7 +600,8 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
 	memset(ah->auth_data, 0, ahp->icv_trunc_len);
 
-	if (ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN))
+	err = ipv6_clear_mutable_options(ip6h, hdr_len, XFRM_POLICY_IN);
+	if (err)
 		goto out_free;
 
 	ip6h->priority    = 0;