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.
Published 2017-10-30 20:29:00
Updated 2018-04-11 01:29:01
Source MITRE
View at NVD,   CVE.org
Vulnerability category: Memory Corruption

Exploit prediction scoring system (EPSS) score for CVE-2017-1000255

0.05%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 18 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2017-1000255

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
6.6
MEDIUM AV:L/AC:L/Au:N/C:N/I:C/A:C
3.9
9.2
NIST
5.5
MEDIUM CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
1.8
3.6
NIST

CWE ids for CVE-2017-1000255

  • The product writes data past the end, or before the beginning, of the intended buffer.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2017-1000255

Products affected by CVE-2017-1000255

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