From: Ira Weiny <ira.weiny@intel.com>
Date: Mon, 10 Aug 2020 17:02:58 -0700
Subject: net/tls: Fix kmap usage
Git-commit: b06c19d9f827f6743122795570bfc0c72db482b0
Patch-mainline: 5.9-rc1
References: networking-stable-20_08_15

When MSG_OOB is specified to tls_device_sendpage() the mapped page is
never unmapped.

Hold off mapping the page until after the flags are checked and the page
is actually needed.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/tls/tls_device.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -560,7 +560,7 @@ int tls_device_sendpage(struct sock *sk,
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct iov_iter	msg_iter;
-	char *kaddr = kmap(page);
+	char *kaddr;
 	struct kvec iov;
 	int rc;
 
@@ -575,6 +575,7 @@ int tls_device_sendpage(struct sock *sk,
 		goto out;
 	}
 
+	kaddr = kmap(page);
 	iov.iov_base = kaddr + offset;
 	iov.iov_len = size;
 	iov_iter_kvec(&msg_iter, WRITE, &iov, 1, size);