CVE-2016-0774 in Android
Summary
by MITRE
The (1) pipe_read and (2) pipe_write implementations in fs/pipe.c in a certain Linux kernel backport in the linux package before 3.2.73-2+deb7u3 on Debian wheezy and the kernel package before 3.10.0-229.26.2 on Red Hat Enterprise Linux (RHEL) 7.1 do not properly consider the side effects of failed __copy_to_user_inatomic and __copy_from_user_inatomic calls, which allows local users to cause a denial of service (system crash) or possibly gain privileges via a crafted application, aka an "I/O vector array overrun." NOTE: this vulnerability exists because of an incorrect fix for CVE-2015-1805.
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Analysis
by VulDB Data Team • 07/27/2022
The vulnerability described in CVE-2016-0774 represents a critical flaw in the Linux kernel's pipe I/O implementation that affects multiple distributions including Debian wheezy and Red Hat Enterprise Linux 7.1. This issue stems from improper handling of memory copy operations within the pipe_read and pipe_write functions located in fs/pipe.c, specifically failing to account for the side effects when __copy_to_user_inatomic and __copy_from_user_inatomic functions return non-zero values indicating failure conditions. The vulnerability is particularly concerning because it was introduced as a flawed attempt to address CVE-2015-1805, creating a regression that exposes systems to both denial of service and privilege escalation attacks.
The technical root cause of this vulnerability lies in the improper error handling of atomic memory copy operations within the kernel's pipe subsystem. When __copy_to_user_inatomic and __copy_from_user_inatomic functions encounter memory access violations or other failures during data transfer between user space and kernel space, they return non-zero values indicating the operation did not complete successfully. However, the pipe_read and pipe_write implementations failed to properly check these return values, leading to potential buffer overruns and memory corruption scenarios. This behavior creates a condition where malicious applications can craft specific I/O vector arrays that trigger these error paths, potentially causing kernel memory corruption that results in system crashes or allows privilege escalation. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited by local users without requiring special privileges or network access.
The operational impact of CVE-2016-0774 extends beyond simple system crashes to include potential privilege escalation capabilities that could allow local attackers to gain elevated system privileges. The I/O vector array overrun condition can be exploited by applications that carefully construct pipe operations with malformed data structures, causing the kernel to process these invalid inputs through the vulnerable code paths. When the kernel fails to properly handle the error conditions returned by atomic memory copy operations, it can lead to memory corruption that manifests as system crashes or more insidiously, provides opportunities for privilege escalation. This vulnerability affects systems running kernel versions before the specified patches, making it particularly relevant for organizations running older Linux distributions that have not received the appropriate security updates.
Mitigation strategies for CVE-2016-0774 require immediate system updates to the patched kernel versions provided by Debian and Red Hat, specifically Debian wheezy systems should upgrade to version 3.2.73-2+deb7u3 and RHEL 7.1 systems to kernel version 3.10.0-229.26.2 or later. Organizations should also implement monitoring for unusual pipe I/O operations that might indicate exploitation attempts and consider implementing kernel lockdown mechanisms to prevent unauthorized modification of kernel memory. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and relates to ATT&CK technique T1068, which covers privilege escalation through kernel exploits. System administrators should also conduct thorough security audits of their kernel configurations and ensure that all systems are running patched versions to prevent exploitation of this vulnerability that could lead to complete system compromise.