netdev - [PATCH net-next] tls: Do not call sk_memcopy_from

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Date:   Fri, 21 Dec 2018 15:16:52 +0000
From:   Vakul Garg <vakul.garg@....com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "borisp@...lanox.com" <borisp@...lanox.com>,
        "aviadye@...lanox.com" <aviadye@...lanox.com>,
        "davejwatson@...com" <davejwatson@...com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "doronrk@...com" <doronrk@...com>, Vakul Garg <vakul.garg@....com>
Subject: [PATCH net-next] 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.

Signed-off-by: Vakul Garg <vakul.garg@....com>
Fixes: d829e9c4112b ("tls: convert to generic sk_msg interface")
---
 net/tls/tls_sw.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 5aee9ae5ca53..11cdc8f7db63 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -943,10 +943,12 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 				    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.
-- 
2.13.6