[PATCHv2 ipsec] xfrm: set dst dev to blackhole_netdev instead of loopback_dev in ifdown

[PATCHv2 ipsec] xfrm: set dst dev to blackhole_netdev instead of loopback_dev in ifdown

[Xin Long]

The global blackhole_netdev has replaced pernet loopback_dev to become the
one given to the object that holds an netdev when ifdown in many places of
ipv4 and ipv6 since commit 8d7017fd621d ("blackhole_netdev: use
blackhole_netdev to invalidate dst entries").

Especially after commit faab39f63c1f ("net: allow out-of-order netdev
unregistration"), it's no longer safe to use loopback_dev that may be
freed before other netdev.

This patch is to set dst dev to blackhole_netdev instead of loopback_dev
in ifdown.

v1->v2:
  - add Fixes tag as Eric suggested.

Fixes: faab39f63c1f ("net: allow out-of-order netdev unregistration")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/xfrm/xfrm_policy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 00bd0ecff5a1..f1876ea61fdc 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3744,7 +3744,7 @@ static int stale_bundle(struct dst_entry *dst)
 void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
 {
 	while ((dst = xfrm_dst_child(dst)) && dst->xfrm && dst->dev == dev) {
-		dst->dev = dev_net(dev)->loopback_dev;
+		dst->dev = blackhole_netdev;
 		dev_hold(dst->dev);
 		dev_put(dev);
 	}
-- 
2.31.1

Re: [PATCHv2 ipsec] xfrm: set dst dev to blackhole_netdev instead of loopback_dev in ifdown

[Eric Dumazet]

On Sun, May 15, 2022 at 6:37 PM Xin Long <lucien.xin@gmail.com> wrote:
>
> The global blackhole_netdev has replaced pernet loopback_dev to become the
> one given to the object that holds an netdev when ifdown in many places of
> ipv4 and ipv6 since commit 8d7017fd621d ("blackhole_netdev: use
> blackhole_netdev to invalidate dst entries").
>
> Especially after commit faab39f63c1f ("net: allow out-of-order netdev
> unregistration"), it's no longer safe to use loopback_dev that may be
> freed before other netdev.
>
> This patch is to set dst dev to blackhole_netdev instead of loopback_dev
> in ifdown.
>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCHv2 ipsec] xfrm: set dst dev to blackhole_netdev instead of loopback_dev in ifdown

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Paolo Abeni <pabeni@redhat.com>:

On Sun, 15 May 2022 21:37:27 -0400 you wrote:
> The global blackhole_netdev has replaced pernet loopback_dev to become the
> one given to the object that holds an netdev when ifdown in many places of
> ipv4 and ipv6 since commit 8d7017fd621d ("blackhole_netdev: use
> blackhole_netdev to invalidate dst entries").
> 
> Especially after commit faab39f63c1f ("net: allow out-of-order netdev
> unregistration"), it's no longer safe to use loopback_dev that may be
> freed before other netdev.
> 
> [...]

Here is the summary with links:
  - [PATCHv2,ipsec] xfrm: set dst dev to blackhole_netdev instead of loopback_dev in ifdown
    https://git.kernel.org/netdev/net/c/4d33ab08c0af

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html