CVE-2022-49291

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

ALSA: pcm: Fix races among concurrent hw_params and hw_free calls

Currently we have neither proper check nor protection against the concurrent calls of PCM hw_params and hw_free ioctls, which may result in a UAF. Since the existing PCM stream lock cant be used for protecting the whole ioctl operations, we need a new mutex to protect those racy calls.

This patch introduced a new mutex, runtime->buffer_mutex, and applies it to both hw_params and hw_free ioctl code paths. Along with it, the both functions are slightly modified (the mmap_count check is moved into the state-check block) for code simplicity.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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/0090c13cbbdffd7da079ac56f80373a9a1be0bf8
• https://git.kernel.org/stable/c/0f6947f5f5208f6ebd4d76a82a4757e2839a23f8
• https://git.kernel.org/stable/c/1bbf82d9f961414d6c76a08f7f843ea068e0ab7b
• https://git.kernel.org/stable/c/33061d0fba51d2bf70a2ef9645f703c33fe8e438
• https://git.kernel.org/stable/c/92ee3c60ec9fe64404dc035e7c41277d74aa26cb
• https://git.kernel.org/stable/c/9cb6c40a6ebe4a0cfc9d6a181958211682cffea9
• https://git.kernel.org/stable/c/a42aa926843acca96c0dfbde2e835b8137f2f092
• https://git.kernel.org/stable/c/fbeb492694ce0441053de57699e1e2b7bc148a69