Re: [syzbot] [net?] WARNING in cleanup_net (3)

From: Hillf Danton
Date: Sat Apr 06 2024 - 18:50:03 EST


On Thu, 04 Apr 2024 20:00:30 -0700
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
> git tree: upstream
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16696223180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e

--- x/include/net/net_namespace.h
+++ y/include/net/net_namespace.h
@@ -318,7 +318,7 @@ static inline int check_net(const struct
return 1;
}

-#define net_drop_ns NULL
+static void net_drop_ns(void *p) {}
#endif


@@ -353,6 +353,7 @@ static inline void __netns_tracker_free(
static inline struct net *get_net_track(struct net *net,
netns_tracker *tracker, gfp_t gfp)
{
+ refcount_inc(&net->passive);
get_net(net);
netns_tracker_alloc(net, tracker, gfp);
return net;
@@ -362,6 +363,7 @@ static inline void put_net_track(struct
{
__netns_tracker_free(net, tracker, true);
put_net(net);
+ net_drop_ns(net);
}

typedef struct {
--