CVE-2022-49474

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

Bluetooth: fix dangling sco_conn and use-after-free in sco_sock_timeout

Connecting the same socket twice consecutively in sco_sock_connect() could lead to a race condition where two sco_conn objects are created but only one is associated with the socket. If the socket is closed before the SCO connection is established, the timer associated with the dangling sco_conn object wont be canceled. As the sock object is being freed, the use-after-free problem happens when the timer callback function sco_sock_timeout() accesses the socket. Heres the call trace:

dump_stack+0x107/0x163 ? refcount_inc+0x1c/ print_address_description.constprop.0+0x1c/0x47e ? refcount_inc+0x1c/0x7b kasan_report+0x13a/0x173 ? refcount_inc+0x1c/0x7b check_memory_region+0x132/0x139 refcount_inc+0x1c/0x7b sco_sock_timeout+0xb2/0x1ba process_one_work+0x739/0xbd1 ? cancel_delayed_work+0x13f/0x13f ? __raw_spin_lock_init+0xf0/0xf0 ? to_kthread+0x59/0x85 worker_thread+0x593/0x70e kthread+0x346/0x35a ? drain_workqueue+0x31a/0x31a ? kthread_bind+0x4b/0x4b ret_from_fork+0x1f/0x30

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References

• https://git.kernel.org/stable/c/36c644c63bfcaee2d3a426f45e89a9cd09799318
• https://git.kernel.org/stable/c/390d82733a953c1fabf3de9c9618091a7a9c90a6
• https://git.kernel.org/stable/c/537f619dea4e3fa8ed1f8f938abffe3615794bcc
• https://git.kernel.org/stable/c/65d347cb39e2e6bd0c2a745ad7c928998ebb0162
• https://git.kernel.org/stable/c/6f55fac0af3531cf60d11369454c41f5fc81ab3f
• https://git.kernel.org/stable/c/7aa1e7d15f8a5b65f67bacb100d8fc033b21efa2
• https://git.kernel.org/stable/c/7d61dbd7311ab978d8ddac1749a758de4de00374
• https://git.kernel.org/stable/c/99df16007f4bbf9abfc3478cb17d10f0d7f8906e
• https://git.kernel.org/stable/c/9de3dc09e56f8deacd2bdbf4cecb71e11a312405