From ca35a0ef85e8ed6df6d5ab01fb6c3530cca0c469 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 24 Oct 2011 01:52:35 -0400 Subject: [PATCH] tcp: md5: dont write skb head in tcp_md5_hash_header() tcp_md5_hash_header() writes into skb header a temporary zero value, this might confuse other users of this area. Since tcphdr is small (20 bytes), copy it in a temporary variable and make the change in the copy. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- net/ipv4/tcp.c | 14 ++++++++------ 2 files changed, 9 insertions(+), 7 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 3edef0bebdd1..910cc29f9e97 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1209,7 +1209,7 @@ extern void tcp_free_md5sig_pool(void); extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); extern void tcp_put_md5sig_pool(void); -extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *); +extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, unsigned header_len); extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 704adad8f07f..eefc61e3d0e4 100644 --- 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); -- 2.34.1