CVE-2025-21772 in Linux
Summary
by MITRE • 02/27/2025
In the Linux kernel, the following vulnerability has been resolved:
partitions: mac: fix handling of bogus partition table
Fix several issues in partition probing:
- The bailout for a bad partoffset must use put_dev_sector(), since the preceding read_part_sector() succeeded. - If the partition table claims a silly sector size like 0xfff bytes (which results in partition table entries straddling sector boundaries), bail out instead of accessing out-of-bounds memory. - We must not assume that the partition table contains proper NUL termination - use strnlen() and strncmp() instead of strlen() and strcmp().
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Analysis
by VulDB Data Team • 05/25/2026
The vulnerability identified as CVE-2025-21772 resides within the Linux kernel's partition handling subsystem, specifically affecting the mac partition table parsing functionality. This issue demonstrates a critical flaw in how the kernel processes partition tables from macintosh-style disk images, where improper validation and memory access patterns could lead to system instability or potential exploitation. The vulnerability impacts systems that utilize mac partition tables, particularly those involving legacy macintosh disk formats or cross-platform disk image handling scenarios.
The technical implementation flaw manifests in three distinct but interconnected issues that collectively weaken the partition table validation process. The first problem involves improper resource management during error conditions where the system fails to properly release sector buffers when encountering invalid partition offsets. This represents a classic resource leak scenario that could lead to memory exhaustion over time, with the fix requiring the use of put_dev_sector() to ensure proper buffer deallocation following successful read_part_sector() operations. The second vulnerability occurs when partition tables specify absurd sector sizes such as 0xfff bytes, which creates a scenario where partition table entries become misaligned across sector boundaries. This misalignment leads to out-of-bounds memory access patterns that could be exploited to read or write data beyond the intended memory regions, representing a direct memory corruption vulnerability. The third issue involves insufficient string validation where the system assumes partition table entries contain proper null termination, a common assumption that can be easily violated in malformed data scenarios.
From an operational impact perspective, this vulnerability creates multiple attack vectors that could be exploited by malicious actors. The resource management issue could lead to denial of service conditions through memory exhaustion, while the memory access violations present opportunities for data corruption or potential code execution. Systems that frequently process disk images or handle mac partition tables would be most at risk, particularly in environments where untrusted input is processed. The vulnerability affects the core kernel partition probing functionality, meaning any application or system component that relies on proper partition table parsing could be impacted. This includes disk management tools, operating system boot loaders, and virtualization platforms that handle macintosh disk formats.
The mitigation strategies for this vulnerability focus on implementing proper defensive programming practices and resource management protocols. The immediate fix requires updating the kernel to include proper error handling for sector buffer management, implementing bounds checking for sector size validation, and utilizing safe string handling functions throughout the partition table parsing code. Organizations should prioritize kernel updates and patch management to address this vulnerability, particularly in environments handling legacy macintosh disk formats or cross-platform disk image processing. The fix aligns with security best practices outlined in the CWE catalog under CWE-704 for improper resource management and CWE-121 for buffer overflow conditions. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation through kernel exploits and resource exhaustion attacks, with potential implications for system availability and data integrity.
This vulnerability demonstrates the critical importance of proper input validation and resource management in kernel space operations. The issues identified represent common security flaws that have been previously documented in various security advisories and vulnerability assessments, emphasizing the need for rigorous code review processes and automated security testing in kernel development. The fix addresses fundamental security principles including proper error handling, bounds checking, and safe string operations, which are essential components of secure coding practices. Organizations should implement comprehensive monitoring for systems that process mac partition tables or disk images, as this vulnerability could potentially be leveraged to gain unauthorized system access or cause system instability through resource exhaustion attacks.