linux-kernel - [PATCH 4.14 089/211] bpf: devmap: fix wrong interface selection in notifier

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Message-Id: <20191127203102.160819159@linuxfoundation.org>
Date:   Wed, 27 Nov 2019 21:30:22 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Taehee Yoo <ap420073@...il.com>,
        Song Liu <songliubraving@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 089/211] bpf: devmap: fix wrong interface selection in notifier_call

From: Taehee Yoo <ap420073@...il.com>

[ Upstream commit f592f804831f1cf9d1f9966f58c80f150e6829b5 ]

The dev_map_notification() removes interface in devmap if
unregistering interface's ifindex is same.
But only checking ifindex is not enough because other netns can have
same ifindex. so that wrong interface selection could occurred.
Hence netdev pointer comparison code is added.

v2: compare netdev pointer instead of using net_eq() (Daniel Borkmann)
v1: Initial patch

Fixes: 2ddf71e23cc2 ("net: add notifier hooks for devmap bpf map")
Signed-off-by: Taehee Yoo <ap420073@...il.com>
Acked-by: Song Liu <songliubraving@...com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/bpf/devmap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 482bf42e21a41..1060eee6c8d5f 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -388,8 +388,7 @@ static int dev_map_notification(struct notifier_block *notifier,
 				struct bpf_dtab_netdev *dev, *odev;
 
 				dev = READ_ONCE(dtab->netdev_map[i]);
-				if (!dev ||
-				    dev->dev->ifindex != netdev->ifindex)
+				if (!dev || netdev != dev->dev)
 					continue;
 				odev = cmpxchg(&dtab->netdev_map[i], dev, NULL);
 				if (dev == odev)
-- 
2.20.1