Ubuntu: USN-2948-2: Linux kernel (Utopic HWE) regression

Description

USN-2948-1 fixed vulnerabilities in the Ubuntu 14.10 Linux kernel backported to Ubuntu 14.04 LTS. An incorrect reference counting fix in the radeon driver introduced a regression that could cause a system crash. This update fixes the problem.

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Original advisory details:

Ralf Spenneberg discovered that the USB driver for Clie devices in the Linux kernel did not properly sanity check the endpoints reported by the device. An attacker with physical access could cause a denial of service (system crash). (CVE-2015-7566) Ralf Spenneberg discovered that the usbvision driver in the Linux kernel did not properly sanity check the interfaces and endpoints reported by the device. An attacker with physical access could cause a denial of service (system crash). (CVE-2015-7833) Venkatesh Pottem discovered a use-after-free vulnerability in the Linux kernel's CXGB3 driver. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2015-8812) It was discovered that a race condition existed in the ioctl handler for the TTY driver in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or expose sensitive information. (CVE-2016-0723) Xiaofei Rex Guo discovered a timing side channel vulnerability in the Linux Extended Verification Module (EVM). An attacker could use this to affect system integrity. (CVE-2016-2085) David Herrmann discovered that the Linux kernel incorrectly accounted file descriptors to the original opener for in-flight file descriptors sent over a unix domain socket. A local attacker could use this to cause a denial of service (resource exhaustion). (CVE-2016-2550) Ralf Spenneberg discovered that the USB driver for Treo devices in the Linux kernel did not properly sanity check the endpoints reported by the device. An attacker with physical access could cause a denial of service (system crash). (CVE-2016-2782) It was discovered that the Linux kernel did not enforce limits on the amount of data allocated to buffer pipes. A local attacker could use this to cause a denial of service (resource exhaustion). (CVE-2016-2847)