CVE-2024-57893: Concurrent Execution using Shared Resource with Improper Synchronization

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

ALSA: seq: oss: Fix races at processing SysEx messages

OSS sequencer handles the SysEx messages split in 6 bytes packets, and ALSA sequencer OSS layer tries to combine those. It stores the data in the internal buffer and this access is racy as of now, which may lead to the out-of-bounds access.

As a temporary band-aid fix, introduce a mutex for serializing the process of the SysEx message packets.