Affected: Linux Kernel

The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line.

This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.

Affected: Ubuntu:22.04:LTS: linux-oem-6.1

It was discovered that the Traffic-Control Index (TCINDEX) implementation in the Linux kernel did not properly perform filter deactivation in some situations. A local attacker could possibly use this to gain elevated privileges. Please note that with the fix for this CVE, kernel support for the TCINDEX classifier has been removed. (CVE-2023-1829)

William Zhao discovered that the Traffic Control (TC) subsystem in the Linux kernel did not properly handle network packet retransmission in certain situations. A local attacker could use this to cause a denial of service (kernel deadlock). (CVE-2022-4269)

Thadeu Cascardo discovered that the io_uring subsystem contained a double- free vulnerability in certain memory allocation error conditions. A local attacker could possibly use this to cause a denial of service (system crash). (CVE-2023-1032)

It was discovered that the TUN/TAP driver in the Linux kernel did not properly initialize socket data. A local attacker could use this to cause a denial of service (system crash). (CVE-2023-1076)

It was discovered that the Real-Time Scheduling Class implementation in the Linux kernel contained a type confusion vulnerability in some situations. A local attacker could use this to cause a denial of service (system crash). (CVE-2023-1077)

It was discovered that the ASUS HID driver in the Linux kernel did not properly handle device removal, leading to a use-after-free vulnerability. A local attacker with physical access could plug in a specia…