linux-kernel - [PATCH 5.1 050/138] xdp: check device pointer before clearing

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Date:   Fri, 12 Jul 2019 14:18:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ilya Maximets <i.maximets@...sung.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 050/138] xdp: check device pointer before clearing

[ Upstream commit 01d76b5317003e019ace561a9b775f51aafdfdc4 ]

We should not call 'ndo_bpf()' or 'dev_put()' with NULL argument.

Fixes: c9b47cc1fabc ("xsk: fix bug when trying to use both copy and zero-copy on one queue id")
Signed-off-by: Ilya Maximets <i.maximets@...sung.com>
Acked-by: Jonathan Lemon <jonathan.lemon@...il.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/xdp/xdp_umem.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 989e52386c35..2f7e2c33a812 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -143,6 +143,9 @@ static void xdp_umem_clear_dev(struct xdp_umem *umem)
 	struct netdev_bpf bpf;
 	int err;
 
+	if (!umem->dev)
+		return;
+
 	if (umem->zc) {
 		bpf.command = XDP_SETUP_XSK_UMEM;
 		bpf.xsk.umem = NULL;
@@ -156,11 +159,9 @@ static void xdp_umem_clear_dev(struct xdp_umem *umem)
 			WARN(1, "failed to disable umem!\n");
 	}
 
-	if (umem->dev) {
-		rtnl_lock();
-		xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
-		rtnl_unlock();
-	}
+	rtnl_lock();
+	xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
+	rtnl_unlock();
 
 	if (umem->zc) {
 		dev_put(umem->dev);
-- 
2.20.1