Re: [PATCH] net_namespace: fixed net_device reference leak
flat view
From: Jojy Varghese <hidden>
Date: 2016-09-08 19:08:31
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
(Updating the patch for the case when a non-loopback dev could be unregistered) Currently during namespace cleanup, if ‘dst’ subsystem is holding a reference to the interface in the namespace, it does not get released. Current code first does a ’dev_hold’ on the same device followed by a ‘dev_put’ on the same device resulting in a no-op. This change fixes this leak by assigning the initial namespace’s loopback device to the ‘dst’ before releasing the reference to the network device being released. Additional reference: https://github.com/docker/docker/issues/5618 Signed-off-by: Jojy G Varghese <redacted> --- net/core/dst.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index a1656e3..7e45593 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c@@ -433,7 +433,11 @@ static void dst_ifdown(struct dst_entry *dst,struct net_device *dev,
dst->input = dst_discard;
dst->output = dst_discard_out;
} else {
- dst->dev = dev_net(dst->dev)->loopback_dev;
+ if (dst->dev == dev_net(dst->dev)->loopback_dev)
+ dst->dev = init_net.loopback_dev;
+ else
+ dst->dev = dev_net(dst->dev)->loopback_dev;
+
dev_hold(dst->dev);
dev_put(dev);
}
--
1.8.3.1
On Wed, Sep 7, 2016 at 6:55 PM, Jojy Varghese [off-list ref] wrote:quoted hunk ↗ jump to hunk
During namespace cleanup, if ‘dst’ subsystem is holding a reference to the loopback interface in the namespace, it does not get released. This is because in the case where the net_device held by 'dst' is same as the namespace's loopback net_device, current code first does a ’dev_hold’ on the same device followed by a ‘dev_put’ on the same device resulting in a no-op. This change fixes this leak by assigning the initial namespace’s loopback device to the ‘dst’’ before releasing the reference to the network device being unregistered. Additional reference: https://github.com/docker/docker/issues/5618 Signed-off-by: Jojy G Varghese <redacted> --- net/core/dst.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/net/core/dst.c b/net/core/dst.c index a1656e3..a18e8ea 100644 --- a/net/core/dst.c +++ b/net/core/dst.c@@ -433,7 +433,7 @@ static void dst_ifdown(struct dst_entry *dst,struct net_device *dev, dst->input = dst_discard; dst->output = dst_discard_out; } else { - dst->dev = dev_net(dst->dev)->loopback_dev; + dst->dev = init_net.loopback_dev; dev_hold(dst->dev); dev_put(dev); } -- 1.8.3.1
-- Jojy G Varghese