Syzbot has reported the following KASAN splat: BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0 Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980 CPU: 0 UID: 0 PID: 4980 Comm: kbnepd bnep0 Not tainted 6.12.0-rc4-00161-gae90f6a6170d #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x100/0x190 ? device_for_each_child+0x18f/0x1a0 print_report+0x13a/0x4cb ? __virt_addr_valid+0x5e/0x590 ? __phys_addr+0xc6/0x150 ? device_for_each_child+0x18f/0x1a0 kasan_report+0xda/0x110 ? device_for_each_child+0x18f/0x1a0 ? __pfx_dev_memalloc_noio+0x10/0x10 device_for_each_child+0x18f/0x1a0 ? __pfx_device_for_each_child+0x10/0x10 pm_runtime_set_memalloc_noio+0xf2/0x180 netdev_unregister_kobject+0x1ed/0x270 unregister_netdevice_many_notify+0x123c/0x1d80 ? __mutex_trylock_common+0xde/0x250 ? __pfx_unregister_netdevice_many_notify+0x10/0x10 ? trace_contention_end+0xe6/0x140 ? __mutex_lock+0x4e7/0x8f0 ? __pfx_lock_acquire.part.0+0x10/0x10 ? rcu_is_watching+0x12/0xc0 ? unregister_netdev+0x12/0x30 unregister_netdevice_queue+0x30d/0x3f0 ? __pfx_unregister_netdevice_queue+0x10/0x10 ? __pfx_down_write+0x10/0x10 unregister_netdev+0x1c/0x30 bnep_session+0x1fb3/0x2ab0 ? __pfx_bnep_session+0x10/0x10 ? __pfx_lock_release+0x10/0x10 ? __pfx_woken_wake_function+0x10/0x10 ? __kthread_parkme+0x132/0x200 ? __pfx_bnep_session+0x10/0x10 ? kthread+0x13a/0x370 ? __pfx_bnep_session+0x10/0x10 kthread+0x2b7/0x370 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x48/0x80 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 4974: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_noprof+0x1d1/0x440 hci_alloc_dev_priv+0x1d/0x2820 __vhci_create_device+0xef/0x7d0 vhci_write+0x2c7/0x480 vfs_write+0x6a0/0xfc0 ksys_write+0x12f/0x260 do_syscall_64+0xc7/0x250 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 4979: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x4f/0x70 kfree+0x141/0x490 hci_release_dev+0x4d9/0x600 bt_host_release+0x6a/0xb0 device_release+0xa4/0x240 kobject_put+0x1ec/0x5a0 put_device+0x1f/0x30 vhci_release+0x81/0xf0 __fput+0x3f6/0xb30 task_work_run+0x151/0x250 do_exit+0xa79/0x2c30 do_group_exit+0xd5/0x2a0 get_signal+0x1fcd/0x2210 arch_do_signal_or_restart+0x93/0x780 syscall_exit_to_user_mode+0x140/0x290 do_syscall_64+0xd4/0x250 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by doing 'device_del()' later and immediately before freeing its 'struct hci_dev' container. Otherwise the former might race against 'unregister_netdev()' innards called when 'bnep_session()' is going to terminate. Reported-by: syzbot+6cf5652d3df49fae2e3f@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f Fixes: bdc3e0f1d201 ("Bluetooth: Move device_add handling into hci_register_dev") Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> --- net/bluetooth/hci_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 96d097b21d13..f1195b110495 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -2716,7 +2716,6 @@ void hci_unregister_dev(struct hci_dev *hdev) rfkill_destroy(hdev->rfkill); } - device_del(&hdev->dev); /* Actual cleanup is deferred until hci_release_dev(). */ hci_dev_put(hdev); } @@ -2756,6 +2755,8 @@ void hci_release_dev(struct hci_dev *hdev) kfree_skb(hdev->sent_cmd); kfree_skb(hdev->req_skb); kfree_skb(hdev->recv_event); + + device_del(&hdev->dev); kfree(hdev); } EXPORT_SYMBOL(hci_release_dev); -- 2.47.0
