CVE-2024-0582 Overview
A use-after-free vulnerability was discovered in the Linux kernel's io_uring functionality. The flaw exists in how a user registers a buffer ring with IORING_REGISTER_PBUF_RING, uses mmap() to map it, and then frees it. This sequence of operations creates a condition where memory can be accessed after being freed, allowing a local user to crash the system or potentially escalate their privileges.
Critical Impact
Local privilege escalation and system crash potential via io_uring buffer ring memory management flaw
Affected Products
- Linux Kernel versions prior to the security patch
- Linux Kernel 6.7-rc1
- Linux Kernel 6.7-rc2
- Linux Kernel 6.7-rc3
Discovery Timeline
- 2024-01-16 - CVE-2024-0582 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2024-0582
Vulnerability Analysis
This vulnerability is classified as CWE-416 (Use After Free), a memory corruption vulnerability that occurs when a program continues to use a pointer after the memory it references has been freed. In this case, the flaw resides within the Linux kernel's io_uring subsystem, specifically in the buffer ring registration and management code.
The io_uring interface is a high-performance asynchronous I/O mechanism in the Linux kernel designed to reduce system call overhead. When a user registers a provided buffer ring using IORING_REGISTER_PBUF_RING and then maps it into user space with mmap(), the kernel allocates and tracks this memory. However, if the user subsequently frees this buffer ring, the memory mapping can persist, creating a use-after-free condition.
This vulnerability requires local access to exploit, meaning an attacker needs an existing foothold on the target system. However, no special privileges are required beyond basic user access, making it particularly concerning in multi-user environments or systems where container escape could be a factor.
Root Cause
The root cause lies in improper memory lifecycle management within the io_uring buffer ring implementation. When a buffer ring is registered and mapped, the kernel should ensure that freeing the buffer properly invalidates all references and mappings. The vulnerable code path fails to correctly handle the relationship between the mmap'd memory region and the underlying buffer ring structure, allowing the memory to be freed while user-space mappings still reference it.
This creates a classic use-after-free scenario where the kernel may reallocate the freed memory for other purposes while user-space code still has a valid mapping to it, potentially allowing an attacker to manipulate kernel memory or cause memory corruption.
Attack Vector
The attack vector for CVE-2024-0582 is local, requiring an attacker to have the ability to execute code on the target system. The exploitation sequence involves:
- Opening an io_uring instance via the io_uring_setup() system call
- Registering a provided buffer ring using IORING_REGISTER_PBUF_RING
- Mapping the buffer ring into user space using mmap()
- Freeing the buffer ring while maintaining the memory mapping
- Manipulating the freed memory through the stale mapping to achieve privilege escalation or cause a denial of service
The vulnerability can be exploited without any user interaction, making it suitable for automated exploitation in local privilege escalation attacks.
Detection Methods for CVE-2024-0582
Indicators of Compromise
- Unexpected system crashes or kernel panics related to io_uring operations
- Suspicious processes making unusual patterns of io_uring system calls
- Memory corruption errors in kernel logs referencing io_uring buffer operations
- Anomalous IORING_REGISTER_PBUF_RING and mmap() sequences followed by immediate unregistration
Detection Strategies
- Monitor for processes using io_uring interfaces in unexpected contexts
- Implement kernel-level audit logging for io_uring_setup(), io_uring_register(), and related system calls
- Deploy runtime security monitoring that detects use-after-free exploitation patterns
- Enable kernel address space layout randomization (KASLR) and other hardening features to make exploitation more difficult
Monitoring Recommendations
- Review kernel logs regularly for io_uring-related errors or warnings
- Implement system call filtering using seccomp to restrict io_uring access for processes that don't require it
- Monitor for privilege escalation attempts following io_uring activity
- Use kernel integrity monitoring tools to detect memory corruption
How to Mitigate CVE-2024-0582
Immediate Actions Required
- Apply the official Linux kernel patch immediately on all affected systems
- Consider temporarily disabling io_uring via kernel parameters on systems where it's not required
- Restrict access to io_uring interfaces using seccomp or AppArmor/SELinux policies
- Prioritize patching systems in multi-tenant environments where local privilege escalation poses the greatest risk
Patch Information
The vulnerability has been addressed in the upstream Linux kernel. The fix is available in commit c392cbecd8eca4c53f2bf508731257d9d0a21c2d in the official Linux kernel Git repository. System administrators should apply kernel updates from their distribution vendors or compile an updated kernel from source.
For additional details and tracking, refer to:
Workarounds
- Disable io_uring at the kernel level using the io_uring_disabled sysctl if the functionality is not required
- Use seccomp filters to block io_uring system calls for unprivileged processes
- Implement container security policies that prevent io_uring access from within containers
- Consider using grsecurity or PaX patches for additional hardening against memory corruption exploits
# Disable io_uring for unprivileged users (requires kernel 5.12+)
echo 2 > /proc/sys/kernel/io_uring_disabled
# Or via sysctl configuration (persistent across reboots)
echo "kernel.io_uring_disabled = 2" >> /etc/sysctl.d/99-io_uring.conf
sysctl -p /etc/sysctl.d/99-io_uring.conf
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
