[PATCH net] udp_tunnel: Fix end of loop test in udp_tunnel_nic_unregister()

[PATCH net] udp_tunnel: Fix end of loop test in udp_tunnel_nic_unregister()

[Dan Carpenter]

This test is checking if we exited the list via break or not.  However
if it did not exit via a break then "node" does not point to a valid
udp_tunnel_nic_shared_node struct.  It will work because of the way
the structs are laid out it's the equivalent of
"if (info->shared->udp_tunnel_nic_info != dev)" which will always be
true, but it's not the right way to test.

Fixes: 74cc6d182d03 ("udp_tunnel: add the ability to share port tables")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 net/ipv4/udp_tunnel_nic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp_tunnel_nic.c b/net/ipv4/udp_tunnel_nic.c
index b91003538d87..bc3a043a5d5c 100644
--- a/net/ipv4/udp_tunnel_nic.c
+++ b/net/ipv4/udp_tunnel_nic.c
@@ -846,7 +846,7 @@ udp_tunnel_nic_unregister(struct net_device *dev, struct udp_tunnel_nic *utn)
 		list_for_each_entry(node, &info->shared->devices, list)
 			if (node->dev == dev)
 				break;
-		if (node->dev != dev)
+		if (list_entry_is_head(node, &info->shared->devices, list))
 			return;
 
 		list_del(&node->list);
-- 
2.20.1

Re: [PATCH net] udp_tunnel: Fix end of loop test in udp_tunnel_nic_unregister()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Tue, 22 Feb 2022 16:42:51 +0300 you wrote:
> This test is checking if we exited the list via break or not.  However
> if it did not exit via a break then "node" does not point to a valid
> udp_tunnel_nic_shared_node struct.  It will work because of the way
> the structs are laid out it's the equivalent of
> "if (info->shared->udp_tunnel_nic_info != dev)" which will always be
> true, but it's not the right way to test.
> 
> [...]

Here is the summary with links:
  - [net] udp_tunnel: Fix end of loop test in udp_tunnel_nic_unregister()
    https://git.kernel.org/netdev/net/c/de7b2efacf4e

You are awesome, thank you!
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