5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima kuniyu@google.com
[ Upstream commit 0725e6afb55128be21a2ca36e9674f573ccec173 ]
syzbot reported use-after-free of tipc_net(net)->monitors[] in tipc_mon_reinit_self(). [0]
The array is protected by RTNL, but tipc_mon_reinit_self() iterates over it without RTNL.
tipc_mon_reinit_self() is called from tipc_net_finalize(), which is always under RTNL except for tipc_net_finalize_work().
Let's hold RTNL in tipc_net_finalize_work().
[0]: BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 Read of size 1 at addr ffff88805eae1030 by task kworker/0:7/5989
CPU: 0 UID: 0 PID: 5989 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: events tipc_net_finalize_work Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568 kasan_check_byte include/linux/kasan.h:399 [inline] lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline] rwbase_rtmutex_lock_state kernel/locking/spinlock_rt.c:160 [inline] rwbase_write_lock+0xd3/0x7e0 kernel/locking/rwbase_rt.c:244 rt_write_lock+0x76/0x110 kernel/locking/spinlock_rt.c:243 write_lock_bh include/linux/rwlock_rt.h:99 [inline] tipc_mon_reinit_self+0x79/0x430 net/tipc/monitor.c:718 tipc_net_finalize+0x115/0x190 net/tipc/net.c:140 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
Allocated by task 6089: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x1a8/0x320 mm/slub.c:4407 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] tipc_mon_create+0xc3/0x4d0 net/tipc/monitor.c:657 tipc_enable_bearer net/tipc/bearer.c:357 [inline] __tipc_nl_bearer_enable+0xe16/0x13f0 net/tipc/bearer.c:1047 __tipc_nl_compat_doit net/tipc/netlink_compat.c:371 [inline] tipc_nl_compat_doit+0x3bc/0x5f0 net/tipc/netlink_compat.c:393 tipc_nl_compat_handle net/tipc/netlink_compat.c:-1 [inline] tipc_nl_compat_recv+0x83c/0xbe0 net/tipc/netlink_compat.c:1321 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:729 ____sys_sendmsg+0x508/0x820 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6088: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kfree+0x195/0x550 mm/slub.c:4894 tipc_l2_device_event+0x380/0x650 net/tipc/bearer.c:-1 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] unregister_netdevice_many_notify+0x14d7/0x1fe0 net/core/dev.c:12166 unregister_netdevice_many net/core/dev.c:12229 [inline] unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12073 unregister_netdevice include/linux/netdevice.h:3385 [inline] __tun_detach+0xe4d/0x1620 drivers/net/tun.c:621 tun_detach drivers/net/tun.c:637 [inline] tun_chr_close+0x10d/0x1c0 drivers/net/tun.c:3433 __fput+0x458/0xa80 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Fixes: 46cb01eeeb86 ("tipc: update mon's self addr when node addr generated") Reported-by: syzbot+d7dad7fd4b3921104957@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/690c323a.050a0220.baf87.007f.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima kuniyu@google.com Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/20251107064038.2361188-1-kuniyu@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/net.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/tipc/net.c b/net/tipc/net.c index 3807ead54d3d5..81c0b123875ae 100644 --- a/net/tipc/net.c +++ b/net/tipc/net.c @@ -141,7 +141,9 @@ void tipc_net_finalize_work(struct work_struct *work) { struct tipc_net *tn = container_of(work, struct tipc_net, work);
+ rtnl_lock(); tipc_net_finalize(tipc_link_net(tn->bcl), tn->trial_addr); + rtnl_unlock(); }
void tipc_net_stop(struct net *net)