CVE-2023-52503

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

tee: amdtee: fix use-after-free vulnerability in amdtee_close_session

There is a potential race condition in amdtee_close_session that may cause use-after-free in amdtee_open_session. For instance, if a session has refcount == 1, and one thread tries to free this session via:

kref_put(&sess->refcount, destroy_session);

the reference count will get decremented, and the next step would be to call destroy_session(). However, if in another thread, amdtee_open_session() is called before destroy_session() has completed execution, alloc_session() may return sess that will be freed up later in destroy_session() leading to use-after-free in amdtee_open_session.

To fix this issue, treat decrement of sess->refcount and removal of sess from session list in destroy_session() as a critical section, so that it is executed atomically.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/1680c82929bc14d706065f123dab77f2f1293116
• https://git.kernel.org/stable/c/1c95574350cd63bc3c5c2fa06658010768f2a0ce
• https://git.kernel.org/stable/c/60c3e7a00db954947c265b55099c21b216f2a05c
• https://git.kernel.org/stable/c/da7ce52a2f6c468946195b116615297d3d113a27
• https://git.kernel.org/stable/c/f4384b3e54ea813868bb81a861bf5b2406e15d8f
• https://git.kernel.org/stable/c/1680c82929bc14d706065f123dab77f2f1293116
• https://git.kernel.org/stable/c/1c95574350cd63bc3c5c2fa06658010768f2a0ce
• https://git.kernel.org/stable/c/60c3e7a00db954947c265b55099c21b216f2a05c
• https://git.kernel.org/stable/c/da7ce52a2f6c468946195b116615297d3d113a27
• https://git.kernel.org/stable/c/f4384b3e54ea813868bb81a861bf5b2406e15d8f