From 6e77a5a4af05d5e7391c841a4a4f3e4cadf72c25 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 8 Feb 2023 18:21:23 +0000 Subject: [PATCH] net: initialize net->notrefcnt_tracker earlier syzbot was able to trigger a warning [1] from net_free() calling ref_tracker_dir_exit(&net->notrefcnt_tracker) while the corresponding ref_tracker_dir_init() has not been done yet. copy_net_ns() can indeed bypass the call to setup_net() in some error conditions. Note: We might factorize/move more code in preinit_net() in the future. [1] INFO: trying to register non-static key. The code is fine but needs lockdep annotation, or maybe you didn't initialize this object before use? turning off the locking correctness validator. CPU: 0 PID: 5817 Comm: syz-executor.3 Not tainted 6.2.0-rc7-next-20230208-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 assign_lock_key kernel/locking/lockdep.c:982 [inline] register_lock_class+0xdb6/0x1120 kernel/locking/lockdep.c:1295 __lock_acquire+0x10a/0x5df0 kernel/locking/lockdep.c:4951 lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5691 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162 ref_tracker_dir_exit+0x52/0x600 lib/ref_tracker.c:24 net_free net/core/net_namespace.c:442 [inline] net_free+0x98/0xd0 net/core/net_namespace.c:436 copy_net_ns+0x4f3/0x6b0 net/core/net_namespace.c:493 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:228 ksys_unshare+0x449/0x920 kernel/fork.c:3205 __do_sys_unshare kernel/fork.c:3276 [inline] __se_sys_unshare kernel/fork.c:3274 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3274 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 Fixes: 0cafd77dcd03 ("net: add a refcount tracker for kernel sockets") Reported-by: syzbot Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230208182123.3821604-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/core/net_namespace.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 078a0a420c8a7..7b69cf882b8ef 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -304,6 +304,12 @@ struct net *get_net_ns_by_id(const struct net *net, int id) } EXPORT_SYMBOL_GPL(get_net_ns_by_id); +/* init code that must occur even if setup_net() is not called. */ +static __net_init void preinit_net(struct net *net) +{ + ref_tracker_dir_init(&net->notrefcnt_tracker, 128); +} + /* * setup_net runs the initializers for the network namespace object. */ @@ -316,7 +322,6 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns) refcount_set(&net->ns.count, 1); ref_tracker_dir_init(&net->refcnt_tracker, 128); - ref_tracker_dir_init(&net->notrefcnt_tracker, 128); refcount_set(&net->passive, 1); get_random_bytes(&net->hash_mix, sizeof(u32)); @@ -472,6 +477,8 @@ struct net *copy_net_ns(unsigned long flags, rv = -ENOMEM; goto dec_ucounts; } + + preinit_net(net); refcount_set(&net->passive, 1); net->ucounts = ucounts; get_user_ns(user_ns); @@ -1118,6 +1125,7 @@ void __init net_ns_init(void) init_net.key_domain = &init_net_key_domain; #endif down_write(&pernet_ops_rwsem); + preinit_net(&init_net); if (setup_net(&init_net, &init_user_ns)) panic("Could not setup the initial network namespace"); -- 2.30.2