[PATCH net] net-sysfs: initialize uid and gid before calling net_ns_get_ownership

Currently in net_ns_get_ownership() it may not be able to set uid or gid
if make_kuid or make_kgid returns an invalid value, and an uninit-value
issue can be triggered by this.

This patch is to fix it by initializing the uid and gid before calling
net_ns_get_ownership(), as it does in kobject_get_ownership()

Fixes: e6dee9f3893c ("net-sysfs: add netdev_change_owner()")
Reported-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/core/net-sysfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index f6197774048b..b2e49eb7001d 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c

@@ -1973,9 +1973,9 @@ int netdev_register_kobject(struct net_device *ndev)
 int netdev_change_owner(struct net_device *ndev, const struct net *net_old,
 			const struct net *net_new)
 {
+	kuid_t old_uid = GLOBAL_ROOT_UID, new_uid = GLOBAL_ROOT_UID;
+	kgid_t old_gid = GLOBAL_ROOT_GID, new_gid = GLOBAL_ROOT_GID;
 	struct device *dev = &ndev->dev;
-	kuid_t old_uid, new_uid;
-	kgid_t old_gid, new_gid;
 	int error;
 
 	net_ns_get_ownership(net_old, &old_uid, &old_gid);

-- 
2.27.0

On Mon, Oct 25, 2021 at 02:31:48AM -0400, Xin Long wrote:

Currently in net_ns_get_ownership() it may not be able to set uid or gid
if make_kuid or make_kgid returns an invalid value, and an uninit-value
issue can be triggered by this.

This patch is to fix it by initializing the uid and gid before calling
net_ns_get_ownership(), as it does in kobject_get_ownership()

Fixes: e6dee9f3893c ("net-sysfs: add netdev_change_owner()")
Reported-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---

Looks good,
Acked-by: Christian Brauner <redacted>

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Mon, 25 Oct 2021 02:31:48 -0400 you wrote:

Currently in net_ns_get_ownership() it may not be able to set uid or gid
if make_kuid or make_kgid returns an invalid value, and an uninit-value
issue can be triggered by this.

This patch is to fix it by initializing the uid and gid before calling
net_ns_get_ownership(), as it does in kobject_get_ownership()

[...]

Here is the summary with links:
  - [net] net-sysfs: initialize uid and gid before calling net_ns_get_ownership
    https://git.kernel.org/netdev/net/c/f7a1e76d0f60

You are awesome, thank you!
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