[PATCH net-next] geneve: fix geneve_config leak on register_netdevice() failure

[PATCH net-next] geneve: fix geneve_config leak on register_netdevice() failure

[Eric Dumazet]

When geneve_configure() allocates a new geneve_config structure via
geneve_config_alloc() and assigns it to geneve->cfg before calling
register_netdevice(), if register_netdevice() fails early (for example,
in dev_get_valid_name() due to an invalid or duplicate interface name),
register_netdevice() exits without calling dev->priv_destructor.

The caller (e.g. rtnl_newlink()) subsequently calls free_netdev(), which
frees the net_device structure directly via kvfree() because reg_state is
NETREG_UNINITIALIZED, bypassing dev->priv_destructor (geneve_free_dev()).
As a result, the newly allocated geneve_config and its per-CPU dst_cache
are leaked.

Fix this by invoking geneve_free_dev(dev) directly on the error path of
register_netdevice(). Since geneve_free_dev() sets geneve->cfg to NULL,
this call is fully idempotent and safe even if register_netdevice()
failed on a later error path that already ran dev->priv_destructor.

Fixes: 0ba269933f73 ("geneve: convert config to RCU-protected pointer")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/geneve.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 17bd3543d587a9e941737109df82b83023d23711..eb156f33b62751b655178ad4f37d2c66f909ffc7 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -2043,8 +2043,10 @@ static int geneve_configure(struct net *net, struct net_device *dev,
 	}
 
 	err = register_netdevice(dev);
-	if (err)
+	if (err) {
+		geneve_free_dev(dev);
 		return err;
+	}
 
 	list_add(&geneve->next, &gn->geneve_list);
 	return 0;
-- 
2.55.0.229.g6434b31f56-goog