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-rw-r--r--net/ipv4/tcp.c14
1 files changed, 8 insertions, 6 deletions
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);