Linux Kernel AppArmor Raw Data Race Condition Vulnerability Leading to Use-After-Free

A race condition vulnerability has been identified in the Linux kernel's AppArmor component, specifically related to the handling of raw data files. This vulnerability arises from the raw data inodes not being properly reference-counted, allowing an attacker to open a raw data file while simultaneously removing the last reference to it by deleting the associated profile. This action frees the memory structure holding the raw data, creating a use-after-free scenario. When the raw data is accessed later, it results in dereferencing a dangling pointer, leading to the exploitation of freed memory. The issue is exacerbated by a timing window during profile removal, where the virtual file system and profile destruction processes interfere with each other, causing the use-after-free condition.

Impact

Exploitation of this vulnerability can lead to a use-after-free condition, where freed memory is accessed, potentially allowing for arbitrary code execution or other memory corruption issues.

Reproduction

To reproduce this vulnerability, load a profile that opens a raw data file while simultaneously removing the last reference to that raw data by deleting the profile. This can be done by using the 'open()' system call on the raw data file and then removing the corresponding profile, which will free the associated memory before the raw data file is closed.

Remediation

Users can update to the latest version of the Linux kernel where this vulnerability has been fixed. Instructions for updating the kernel can be found in the official Linux kernel documentation.