CVE-2022-49493

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

ASoC: rt5645: Fix errorenous cleanup order

There is a logic error when removing rt5645 device as the function rt5645_i2c_remove() first cancel the &rt5645->jack_detect_work and delete the &rt5645->btn_check_timer latter. However, since the timer handler rt5645_btn_check_callback() will re-queue the jack_detect_work, this cleanup order is buggy.

That is, once the del_timer_sync in rt5645_i2c_remove is concurrently run with the rt5645_btn_check_callback, the canceled jack_detect_work will be rescheduled again, leading to possible use-after-free.

This patch fix the issue by placing the del_timer_sync function before the cancel_delayed_work_sync.

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/061a6159cea583f1155f67d1915917a6b9282662
• https://git.kernel.org/stable/c/0941150100173d4eaf3fe08ff4b16740e7c3026f
• https://git.kernel.org/stable/c/1a5a3dfd9f172dcb115072f0aea5e27d3083c20e
• https://git.kernel.org/stable/c/236d29c5857f02e0a53fdf15d3dce1536c4322ce
• https://git.kernel.org/stable/c/2def44d3aec59e38d2701c568d65540783f90f2f
• https://git.kernel.org/stable/c/453f0920ffc1a28e28ddb9c3cd5562472b2895b0
• https://git.kernel.org/stable/c/7d801e807536a9a9c2146c5f4a5836f154517ed3
• https://git.kernel.org/stable/c/88c09e4812d72c3153afc8e5a45ecac2d0eae3ff
• https://git.kernel.org/stable/c/abe7554da62cb489712a54de69ef5665c250e564