CVE-2022-50419

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_sysfs: Fix attempting to call device_add multiple times

device_add shall not be called multiple times as stated in its documentation:

'Do not call this routine or device_register() more than once for any device structure'

Syzkaller reports a bug as follows [1]: ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:33! invalid opcode: 0000 [#1] PREEMPT SMP KASAN [...] Call Trace: <TASK> __list_add include/linux/list.h:69 [inline] list_add_tail include/linux/list.h:102 [inline] kobj_kset_join lib/kobject.c:164 [inline] kobject_add_internal+0x18f/0x8f0 lib/kobject.c:214 kobject_add_varg lib/kobject.c:358 [inline] kobject_add+0x150/0x1c0 lib/kobject.c:410 device_add+0x368/0x1e90 drivers/base/core.c:3452 hci_conn_add_sysfs+0x9b/0x1b0 net/bluetooth/hci_sysfs.c:53 hci_le_cis_estabilished_evt+0x57c/0xae0 net/bluetooth/hci_event.c:6799 hci_le_meta_evt+0x2b8/0x510 net/bluetooth/hci_event.c:7110 hci_event_func net/bluetooth/hci_event.c:7440 [inline] hci_event_packet+0x63d/0xfd0 net/bluetooth/hci_event.c:7495 hci_rx_work+0xae7/0x1230 net/bluetooth/hci_core.c:4007 process_one_work+0x991/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 </TASK>

The bug in hci_sysfs.c allowed device_add() to be called multiple times for the same Bluetooth connection object, violating the kernel’s device model contract and leading to a kernel BUG due to list corruption (__list_add in lib/list_debug.c). This could result in a kernel crash or panic when duplicate additions were attempted, for example after repeated LE CIS establishment events. The issue can be triggered by local processes or fuzzers (e.g. syzkaller) capable of manipulating HCI events, but it requires local access and privileges to interact with the Bluetooth subsystem.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.