[PATCH] net/tls: move version check after second userspace fetch

[Meng Xu]

Even the userspace buffer optval passed the version check
(i.e., tmp_crypto_info.version == TLS_1_2_VERSION) after the first fetch,
it can still be changed before the second copy_from_user() and hence,
a version different than TLS_1_2_VERSION may be copied into crypto_info.
This patch moves the version check after the second userspace fetch.

Signed-off-by: Meng Xu <mengxu.gat...@gmail.com>
---
 net/tls/tls_main.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 60aff60..d4a7bc6 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -354,12 +354,6 @@ static int do_tls_setsockopt_tx(struct sock *sk, char 
__user *optval,
                goto out;
        }
 
-       /* check version */
-       if (tmp_crypto_info.version != TLS_1_2_VERSION) {
-               rc = -ENOTSUPP;
-               goto out;
-       }
-
        /* get user crypto info */
        crypto_info = &ctx->crypto_send;
 
@@ -382,6 +376,12 @@ static int do_tls_setsockopt_tx(struct sock *sk, char 
__user *optval,
                        rc = -EFAULT;
                        goto err_crypto_info;
                }
+
+               /* check version */
+               if (crypto_info->version != TLS_1_2_VERSION) {
+                       rc = -ENOTSUPP;
+                       goto err_crypto_info;
+               }
                break;
        }
        default:
-- 
2.7.4