Loop with Unreachable Exit Condition ('Infinite Loop') Affecting kernel-64k-debug package, versions <0:5.14.0-503.11.1.el9_5


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL9-KERNEL64KDEBUG-6275021
  • published25 Feb 2024
  • disclosed24 Feb 2024

Introduced: 24 Feb 2024

CVE-2024-26603  (opens in a new tab)
CWE-835  (opens in a new tab)

How to fix?

Upgrade RHEL:9 kernel-64k-debug to version 0:5.14.0-503.11.1.el9_5 or higher.
This issue was patched in RHSA-2024:9315.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-debug package and not the kernel-64k-debug package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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 fx_sw->xstate_size. fx_sw->xstate_size can be changed from user-space, so it is possible construct a sigreturn frame where:

  • fx_sw->xstate_size is smaller than the size required by valid bits in fx_sw->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 fault_in_readable succeeds because buf + fx_sw->xstate_size 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->user_size).

[ dhansen: tweak subject / changelog ]

CVSS Scores

version 3.1