CVE-2022-1786 in Android
Summary
by MITRE • 06/02/2022
A use-after-free flaw was found in the Linux kernel’s io_uring subsystem in the way a user sets up a ring with IORING_SETUP_IOPOLL with more than one task completing submissions on this ring. This flaw allows a local user to crash or escalate their privileges on the system.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/31/2022
The vulnerability identified as CVE-2022-1786 represents a critical use-after-free flaw within the Linux kernel's io_uring subsystem, specifically affecting systems that utilize the IORING_SETUP_IOPOLL flag for asynchronous I/O operations. This flaw exists in the kernel's handling of ring setup configurations where multiple tasks attempt to complete submissions simultaneously on the same polling ring. The io_uring subsystem serves as a high-performance asynchronous I/O interface that enables applications to efficiently handle large volumes of I/O operations without traditional system call overhead. When combined with the IORING_SETUP_IOPOLL flag, which enables polling-based I/O completion, the vulnerability becomes exploitable through improper memory management during concurrent access scenarios.
The technical root cause of this vulnerability stems from improper memory deallocation and reference management within the kernel's io_uring implementation. When multiple tasks concurrently submit operations to a ring configured with IORING_SETUP_IOPOLL, the kernel fails to properly synchronize access to shared memory structures, leading to a situation where freed memory regions are still being referenced by subsequent operations. This use-after-free condition occurs during the handling of completion events and submission processing, where the kernel's memory management logic does not adequately prevent access to deallocated structures. The flaw manifests as a race condition between task completion handlers and memory deallocation routines, creating opportunities for memory corruption that can be leveraged by malicious actors.
From an operational perspective, this vulnerability presents a significant threat to system integrity and availability, as it allows local users to either cause system crashes through kernel panics or escalate their privileges to root level access. The local privilege escalation aspect makes this particularly dangerous in multi-user environments where untrusted users might be present, as successful exploitation could provide attackers with complete control over affected systems. The impact extends beyond simple denial of service, as the vulnerability can be exploited to bypass security boundaries and potentially compromise entire system infrastructures. The vulnerability affects systems running Linux kernel versions where the io_uring subsystem is enabled and actively used with the specified polling configuration.
Security mitigations for CVE-2022-1786 primarily involve applying the latest kernel updates from trusted sources, as the vulnerability has been addressed through patches that correct the memory management logic in the io_uring subsystem. Organizations should prioritize kernel updates and conduct thorough testing in controlled environments before deployment to ensure compatibility with existing applications. Additionally, system administrators can implement monitoring solutions to detect unusual patterns in I/O operations that might indicate exploitation attempts, though such measures provide only detection capabilities rather than prevention. The vulnerability aligns with CWE-416, which describes use-after-free conditions in software, and represents a significant concern within the ATT&CK framework under privilege escalation techniques, specifically targeting the kernel-level execution environment to gain elevated system privileges.