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Linux KernelOperating system · Linux

CVE-2017-1000255

MEDIUM · 5.5 CVSS v3.0 Published 2017-10-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

On PowerPC (Power8+) Linux systems, a local attacker can craft a malicious signal frame containing a controlled r1 (stack pointer) value. When sigreturn is called, the kernel uses this attacker-supplied r1 during exception handling, causing kernel stack data to be written to arbitrary memory locations. This allows privilege escalation via arbitrary memory overwrite. Kernels with CONFIG_PPC_TRANSACTIONAL_MEM=n are not vulnerable.

MitigationApply the upstream kernel patch for commit 5d176f751ee3, or rebuild the kernel with CONFIG_PPC_TRANSACTIONAL_MEM=n to disable the vulnerable code path.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify PowerPC architecture
    Check /proc/cpuinfo for 'cpu' field or run 'uname -m' - look for ppc64le or ppc64
    Affected if System is not running on PowerPC architecture (the vulnerability only affects PowerPC)
  2. Confirm Power8 or later processor
    Run 'cat /proc/cpuinfo | grep -i power8' or check the 'cpu' line in /proc/cpuinfo for P8, POWER8 or higher
    Affected if Processor is Power7 or earlier (vulnerability requires Power8 or later)
  3. Check kernel transactional memory config
    Check if CONFIG_PPC_TRANSACTIONAL_MEM is enabled: grep -i CONFIG_PPC_TRANSACTIONAL_MEM /boot/config-$(uname -r) or cat /proc/config.gz | grep CONFIG_PPC_TRANSACTIONAL_MEM
    Affected if CONFIG_PPC_TRANSACTIONAL_MEM=y is set (vulnerable); CONFIG_PPC_TRANSACTIONAL_MEM=n means not affected
  4. Verify kernel version
    Run 'uname -r' to get kernel version for context
    Affected if All versions on vulnerable Power8+ systems with CONFIG_PPC_TRANSACTIONAL_MEM=y

System is affected only if it runs on PowerPC Power8+ architecture AND has CONFIG_PPC_TRANSACTIONAL_MEM=y enabled in the kernel configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the upstream kernel patch for commit 5d176f751ee3, or rebuild the kernel with CONFIG_PPC_TRANSACTIONAL_MEM=n to disable the vulnerable code path.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-1000255 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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