CVE-2016-9644

The __get_user_asm_ex macro in arch/x86/include/asm/uaccess.h in the Linux kernel 4.4.22 through 4.4.28 contains extended asm statements that are incompatible with the exception table, which allows local users to obtain root access on non-SMEP platforms via a crafted application. NOTE: this vulnerability exists because of incorrect backporting of the CVE-2016-9178 patch to older kernels.

From the Ubuntu Security Team

It was discovered that the __get_user_asm_ex implementation in the Linux kernel for x86/x86_64 contained extended asm statements that were incompatible with the exception table. A local attacker could use this to gain administrative privileges.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
linux	16.10 yakkety	Not affected
	16.04 LTS xenial	Fixed 4.4.0-51.72
	14.04 LTS trusty	Vulnerable, work in progress
	12.04 LTS precise	Not affected
linux-armadaxp	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not affected
linux-aws	16.10 yakkety	Not in release
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected
	12.04 LTS precise	Not in release
linux-flo	16.10 yakkety	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-gke	16.10 yakkety	Not in release
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-goldfish	16.10 yakkety	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-grouper	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-hwe	16.10 yakkety	Not in release
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-hwe-edge	16.10 yakkety	Not in release
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-linaro-omap	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-linaro-shared	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-linaro-vexpress	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-lts-quantal	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-lts-raring	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-lts-saucy	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-lts-trusty	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not affected
linux-lts-utopic	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-lts-vivid	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-lts-wily	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-lts-xenial	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Fixed 4.4.0-51.72~14.04.1
	12.04 LTS precise	Not in release
linux-maguro	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-mako	16.10 yakkety	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-manta	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-qcm-msm	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Ignored end of life
linux-raspi2	16.10 yakkety	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-snapdragon	16.10 yakkety	Fixed 4.4.0-1046.50
	16.04 LTS xenial	Fixed 4.4.0-1042.46
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release
linux-ti-omap4	16.10 yakkety	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not affected

Notes

sbeattie

1c109fabbd51863475cd12ac206bdd249aee35af was applied to the 4.4 stable series (in xenial as 1c109fabbd51863475cd12ac206bdd249aee35af) to fix CVE-2016-9178, and then got reverted from stable in 4.4.30 (in xenial as 2da13e7f631bb13658e00e61fdea050da25e69e7). 548acf19234dbda5a52d5a8e7e205af46e9da840 was also very briefly applied to stable in 4.4.29, but reverted at the same time due to problems (in xenial as 102d19689b2dd4f639a14dfd3f52ce19b5d7bb17). For xenial/4.4 derived kernels, this CVE is fixed with the reversion in 2da13e7f631bb13658e00e61fdea050da25e69e7. However, this leaves CVE-2016-9178 unfixed.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
linux	Introduced by 1c109fa, fixed by 548acf1

Severity score breakdown

Parameter	Value
Base score	7.8 · High
Attack vector	Local
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-3161-4
Linux kernel (Qualcomm Snapdragon) vulnerabilities
20 December 2016

USN-3146-2
Linux kernel (Xenial HWE) vulnerabilities
30 November 2016

USN-3146-1
Linux kernel vulnerabilities
30 November 2016

Cvss 3 Severity Score