ALSA: pcm: Fix potential data race at PCM memory allocation helpers

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix potential data race at PCM memory allocation helpers The PCM memory allocation helpers have a sanity check against too many buffer allocations. However, the check is performed without a proper lock and the allocation isn't serialized; this allows user to allocate more memories than predefined max size. Practically seen, this isn't really a big problem, as it's more or less some "soft limit" as a sanity check, and it's not possible to allocate unlimitedly. But it's still better to address this for more consistent behavior. The patch covers the size check in do_alloc_pages() with the card->memory_mutex, and increases the allocated size there for preventing the further overflow. When the actual allocation fails, the size is decreased accordingly.

References

• https://git.kernel.org/stable/c/7e1d1456c8db9949459c5a24e8845cfe92430b0f
• https://git.kernel.org/stable/c/7e11c58b2620a22c67a5ae28d64ce383890ee9f4
• https://git.kernel.org/stable/c/a0ab49e7a758b488b2090171a75d50735c0876f6
• https://git.kernel.org/stable/c/3eb4e47a94e3f76521d7d344696db61e6a9619c7
• https://git.kernel.org/stable/c/773ccad902f67583a58b5650a2f8d8daf2e76fac
• https://git.kernel.org/stable/c/bd55842ed998a622ba6611fe59b3358c9f76773d