On Tue, 23 May 2023 17:46:20 +0200 Jason A. Donenfeld wrote: > > Freed by task 41: > > __kmem_cache_free+0x264/0x3c0 mm/slub.c:3799 > > device_release+0x95/0x1c0 > > kobject_cleanup lib/kobject.c:683 [inline] > > kobject_release lib/kobject.c:714 [inline] > > kref_put include/linux/kref.h:65 [inline] > > kobject_put+0x228/0x470 lib/kobject.c:731 > > netdev_run_todo+0xe5a/0xf50 net/core/dev.c:10400 > > So that means the memory in question is actually the one that's > allocated and freed by the networking stack. Specifically, dev.c:10626 > is allocating a struct net_device with a trailing struct wg_device (its > priv_data). However, wg_device does not have any struct timer_lists in > it, and I don't see how net_device's watchdog_timer would be related to > the stacktrace which is clearly operating over a wg_peer timer. > > So what on earth is going on here?
Your timer had the pleasure of getting queued _after_ a dead watchdog timer, no? IOW it tries to update the ->next pointer of a queued watchdog timer. We should probably do: diff --git a/net/core/dev.c b/net/core/dev.c index 374d38fb8b9d..f3ed20ebcf5a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10389,6 +10389,8 @@ void netdev_run_todo(void) WARN_ON(rcu_access_pointer(dev->ip_ptr)); WARN_ON(rcu_access_pointer(dev->ip6_ptr)); + WARN_ON(timer_shutdown_sync(&dev->watchdog_timer)); + if (dev->priv_destructor) dev->priv_destructor(dev); if (dev->needs_free_netdev) to catch how that watchdog_timer is getting queued. Would that make sense, Eric?