CVE-2017-1000255

Description

On Linux running on PowerPC hardware (Power8 or later) a user process can craft a signal frame and then do a sigreturn so that the kernel will take an exception (interrupt), and use the r1 value *from the signal frame* as the kernel stack pointer. As part of the exception entry the content of the signal frame is written to the kernel stack, allowing an attacker to overwrite arbitrary locations with arbitrary values. The exception handling does produce an oops, and a panic if panic_on_oops=1, but only after kernel memory has been over written. This flaw was introduced in commit: "5d176f751ee3 (powerpc: tm: Enable transactional memory (TM) lazily for userspace)" which was merged upstream into v4.9-rc1. Please note that kernels built with CONFIG_PPC_TRANSACTIONAL_MEM=n are not vulnerable.

Category

5.5
CVSS
Severity: Medium
CVSS 3.0 •
CVSS 2.0 •
EPSS 0.05%
Vendor Advisory redhat.com
Affected: n/a n/a
Published at:
Updated at:

References

Link Tags
https://access.redhat.com/errata/RHSA-2018:0654 vendor advisory
https://access.redhat.com/security/cve/CVE-2017-1000255 third party advisory issue tracking
http://www.securityfocus.com/bid/101264 third party advisory vdb entry

Frequently Asked Questions

What is the severity of CVE-2017-1000255?
CVE-2017-1000255 has been scored as a medium severity vulnerability.
How to fix CVE-2017-1000255?
To fix CVE-2017-1000255, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2017-1000255 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2017-1000255 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
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