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.
CVSS Details
- CVSS 3.0 Base Score: 5.5
- CVSS 3.0 Vector: (CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux | — | Upgrade kernel | Nov 21, 2017 | Oct 10, 2017 |
| Centos_linux | — | Upgrade kernel | Aug 28, 2019 | Oct 30, 2017 |
| Debian | — | Upgrade linux | Jul 30, 2024 | Oct 30, 2017 |
| Redhat_linux | — | Upgrade kernel | Apr 11, 2018 | Oct 10, 2017 |
| Suse | — | Upgrade kernel-docsUpgrade kernel-default-manUpgrade kernel-defaultUpgrade gfs2-kmp-defaultUpgrade ocfs2-kmp-defaultUpgrade dlm-kmp-defaultUpgrade kernel-azure-baseUpgrade cluster-md-kmp-defaultUpgrade kernel-default-extraUpgrade kernel-source-azureUpgrade kernel-devel-azureUpgrade kernel-obs-build | May 20, 2018 | Oct 10, 2017 |
| Ubuntu | — | Upgrade linux-image-lowlatency-hwe-16.04Upgrade linux-image-genericUpgrade linux-image-4.13.0-17-genericUpgrade linux-image-4.13.0-1006-raspi2Upgrade linux-image-generic-hwe-16.04Upgrade linux-image-lowlatencyUpgrade linux-image-powerpc-e500mcUpgrade linux-image-generic-lpaeUpgrade linux-image-4.10.0-37-generic-lpaeUpgrade linux-image-4.10.0-37-genericUpgrade linux-image-generic-lpae-hwe-16.04Upgrade linux-image-powerpc64-smpUpgrade linux-image-4.10.0-1019-raspi2Upgrade linux-image-powerpc64-embUpgrade linux-image-virtualUpgrade linux-image-powerpc-smpUpgrade linux-image-raspi2Upgrade linux-image-4.13.0-17-generic-lpaeUpgrade linux-image-4.10.0-37-lowlatencyUpgrade linux-image-4.13.0-17-lowlatency | Oct 10, 2017 | Oct 10, 2017 |
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