CVE-2021-47096: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47096 affects the Linux kernel's ALSA (Advanced Linux Sound Architecture) rawmidi component. The vulnerability was discovered when an uninitialized user_pversion variable was found in the user space file structure during the open function. This occurred because the file private structure used kmalloc for allocation without proper initialization. The vulnerability was disclosed on March 4, 2024, and affects Linux kernel systems using the ALSA rawmidi component (NVD).

The vulnerability stems from a failure to initialize the user_pversion field in the rawmidi file structure when allocating memory using kmalloc. The issue was introduced in the commit that added SNDRV_RAWMIDI_IOCTL_USER_PVERSION functionality. The vulnerability has been assigned a CVSS v3.1 base score of 4.0 (Medium) with the vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (NVD).

The vulnerability could potentially lead to information disclosure due to the use of uninitialized memory. Since the kernel ALSA sequencer code clears the file structure, the impact is limited to the rawmidi component (Kernel Commit).

The vulnerability requires local access to the system and can be triggered through the ALSA rawmidi interface. No known exploits have been reported in the wild (NVD).

The vulnerability has been fixed by initializing the user_pversion field to 0 during the file structure allocation in the snd_rawmidi_open function. The fix was implemented in the Linux kernel through a patch that adds the initialization code (Kernel Commit).