[PATCH] net/tls: Fix kmap usage

[PATCH] net/tls: Fix kmap usage

[ira.weiny]

From: Ira Weiny <ira.weiny@intel.com>

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.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 net/tls/tls_device.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index 0e55f8365ce2..0cbad566f281 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -561,7 +561,7 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
 {
 	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;
 
@@ -576,6 +576,7 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
 		goto out;
 	}
 
+	kaddr = kmap(page);
 	iov.iov_base = kaddr + offset;
 	iov.iov_len = size;
 	iov_iter_kvec(&msg_iter, WRITE, &iov, 1, size);
-- 
2.28.0.rc0.12.gb6a658bd00c9

Re: [PATCH] net/tls: Fix kmap usage

[Jakub Kicinski]

On Mon, 10 Aug 2020 17:02:58 -0700 ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> When MSG_OOB is specified to tls_device_sendpage() the mapped page is
> never unmapped.

Nice catch!

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

We could take the kmap/kunmap from under the socket lock, but that'd
perhaps be more code reshuffling than we need in a fix.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Reviewed-by: Jakub Kicinski <kuba@kernel.org>

Re: [PATCH] net/tls: Fix kmap usage

[David Miller]

From: ira.weiny@intel.com
Date: Mon, 10 Aug 2020 17:02:58 -0700

> From: Ira Weiny <ira.weiny@intel.com>
> 
> 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.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Applied and queued up for -stable, thank you.