tls: Do not call sk_memcopy_from_iter with zero length

In some conditions e.g. when tls_clone_plaintext_msg() returns -ENOSPC,
the number of bytes to be copied using subsequent function
sk_msg_memcopy_from_iter() becomes zero. This causes function
sk_msg_memcopy_from_iter() to fail which in turn causes tls_sw_sendmsg()
to return failure. To prevent it, do not call sk_msg_memcopy_from_iter()
when number of bytes to copy (indicated by 'try_to_copy') is zero.

Fixes: d829e9c4112b ("tls: convert to generic sk_msg interface")
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 7b1af8b..29b2785 100644 (file)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -935,10 +935,12 @@ fallback_to_reg_send:
                                    tls_ctx->tx.overhead_size);
                }
 
-               ret = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_pl,
-                                              try_to_copy);
-               if (ret < 0)
-                       goto trim_sgl;
+               if (try_to_copy) {
+                       ret = sk_msg_memcopy_from_iter(sk, &msg->msg_iter,
+                                                      msg_pl, try_to_copy);
+                       if (ret < 0)
+                               goto trim_sgl;
+               }
 
                /* Open records defined only if successfully copied, otherwise
                 * we would trim the sg but not reset the open record frags.