tcp: md5: dont write skb head in tcp_md5_hash_header()

[pandora-kernel.git] / net / ipv4 / tcp.c

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 704adad..eefc61e 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2994,17 +2994,19 @@ void tcp_put_md5sig_pool(void)
 EXPORT_SYMBOL(tcp_put_md5sig_pool);
 
 int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
-                       struct tcphdr *th)
+                       const struct tcphdr *th)
 {
        struct scatterlist sg;
+       struct tcphdr hdr;
        int err;
 
-       __sum16 old_checksum = th->check;
-       th->check = 0;
+       /* We are not allowed to change tcphdr, make a local copy */
+       memcpy(&hdr, th, sizeof(hdr));
+       hdr.check = 0;
+
        /* options aren't included in the hash */
-       sg_init_one(&sg, th, sizeof(struct tcphdr));
-       err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
-       th->check = old_checksum;
+       sg_init_one(&sg, &hdr, sizeof(hdr));
+       err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(hdr));
        return err;
 }
 EXPORT_SYMBOL(tcp_md5_hash_header);