CVE-2019-18660: Infoleak
A flaw was found in the way the Linux kernel implemented a software flush of the Count Cache (indirect branch cache) and Link (Return Address) Stack on the PowerPC platform. The flushing of these structures helps to prevent SpectreRSB like attacks which may leak information from one user process to another. An unprivileged user could use this flaw to cross the syscall or process boundary and read privileged memory by conducting targeted cache side-channel attacks.
Other sources
An issue was found in the way Linux kernel implemented software flush of the Count Cache (indirect branch cache) and Link (Return Address) Stack on PowerPC platform. The flushing of these structures helps to prevent SpectreRSB like attacks which may leak information from one user process to another.
An unprivileged user could use this flaw to cross the syscall or process boundary and read privileged memory by conducting targeted cache side-channel attacks.
Upstream commit: ---------------- -> https://git.kernel.org/linus/39e72bf96f5847ba87cc5bd7a3ce0fed813dc9ad -> https://git.kernel.org/linus/af2e8c68b9c5403f77096969c516f742f5bb29e0
References: ----------- -> https://www.openwall.com/lists/oss-security/2019/11/27/1
— Red Hat
Linux Kernel for PowerPC could allow a local authenticated attacker to obtain sensitive information, caused by the failure to activate the mitigation for Spectre-RSB on context switch. By using side channel attacks, an attacker could exploit this vulnerability to obtain sensitive information, and use this information to launch further attacks against the affected system.
— IBM
The Linux kernel before 5.4.1 on powerpc allows Information Exposure because the Spectre-RSB mitigation is not in place for all applicable CPUs, aka CID-39e72bf96f58. This is related to arch/powerpc/kernel/entry64.S and arch/powerpc/kernel/security.c.
Affected Software
Remediation
Patch Available
Patch Available
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2019-18660?
CVE-2019-18660 is rated as a medium-severity vulnerability in the Linux kernel impacting the PowerPC platform.
How do I fix CVE-2019-18660?
To fix CVE-2019-18660, update your Linux kernel to the appropriate remedial version for your distribution.
Which systems are affected by CVE-2019-18660?
CVE-2019-18660 affects various versions of the Linux kernel, including certain Red Hat, Ubuntu, Fedora, and openSUSE systems.
What type of vulnerability is CVE-2019-18660?
CVE-2019-18660 is a flaw related to insufficient flushing of the Count Cache and Link Stack, potentially leading to information leaks.
Can I still use my system if it is affected by CVE-2019-18660?
While you can still use your system, it is strongly recommended to apply the necessary patches to mitigate the risk of exploitation.