CVE-2024-26603: x86/fpu: Stop relying on userspace for info to fault in xsave buffer
In the Linux kernel, the following vulnerability has been resolved:
x86/fpu: Stop relying on userspace for info to fault in xsave buffer
Before this change, the expected size of the user space buffer was taken from fxsw->xstatesize. fxsw->xstatesize can be changed from user-space, so it is possible construct a sigreturn frame where:
fxsw->xstatesize is smaller than the size required by valid bits in fxsw->xfeatures. user-space unmaps parts of the sigrame fpu buffer so that not all of the buffer required by xrstor is accessible.
In this case, xrstor tries to restore and accesses the unmapped area which results in a fault. But faultinreadable succeeds because buf + fxsw->xstatesize is within the still mapped area, so it goes back and tries xrstor again. It will spin in this loop forever.
Instead, fault in the maximum size which can be touched by XRSTOR (taken from fpstate->usersize).
[ dhansen: tweak subject / changelog ]
Other sources
In the Linux kernel, the following vulnerability has been resolved:
x86/fpu: Stop relying on userspace for info to fault in xsave buffer
The Linux kernel CVE team has assigned CVE-2024-26603 to this issue.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2024022415-CVE-2024-26603-42c2@gregkh/T/#u
— Red Hat
Linux Kernel is vulnerable to a denial of service, caused by the reliance of userspace for info to fault in xsave buffer. A local attacker could exploit this vulnerability to cause a segmentation fault.
— IBM
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-26603?
CVE-2024-26603 is identified as an important-level vulnerability in the Linux kernel.
How do I fix CVE-2024-26603?
To fix CVE-2024-26603, update your Linux kernel to version 6.1.79 or later, or apply the latest patches for your specific distribution.
Which Linux kernel versions are affected by CVE-2024-26603?
CVE-2024-26603 affects Linux kernel versions from 5.14.0 up to 6.1.79.
What components are impacted by CVE-2024-26603?
CVE-2024-26603 affects the x86 floating-point unit (fpu) functionality within the Linux kernel.
Is CVE-2024-26603 a remote or local vulnerability?
CVE-2024-26603 is considered a local vulnerability, requiring an attacker to have local access to exploit.