CVE-2024-35871 — riscv: process: Fix kernel gp leakage

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

riscv: process: Fix kernel gp leakage

childregs represents the registers which are active for the new thread in user context. For a kernel thread, childregs->gp is never used since the kernel gp is not touched by switch_to. For a user mode helper, the gp value can be observed in user space after execve or possibly by other means.

[From the email thread]

The /* Kernel thread */ comment is somewhat inaccurate in that it is also used for user_mode_helper threads, which exec a user process, e.g. /sbin/init or when /proc/sys/kernel/core_pattern is a pipe. Such threads do not have PF_KTHREAD set and are valid targets for ptrace etc. even before they exec.

childregs is the *user* context during syscall execution and it is observable from userspace in at least five ways:

1. kernel_execve does not currently clear integer registers, so the starting register state for PID 1 and other user processes started by the kernel has sp = user stack, gp = kernel __global_pointer$, all other integer registers zeroed by the memset in the patch comment.

This is a bug in its own right, but I'm unwilling to bet that it is the only way to exploit the issue addressed by this patch.

2. ptrace(PTRACE_GETREGSET): you can PTRACE_ATTACH to a user_mode_helper thread before it execs, but ptrace requires SIGSTOP to be delivered which can only happen at user/kernel boundaries.

3. /proc/*/task/*/syscall: this is per…

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities

Affected: Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-azure, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-intel, Ubuntu:24.04:LTS: linux-lowlatency, Ubuntu:24.04:LTS: linux-oem-6.8, Ubuntu:24.04:LTS: linux-raspi

It was discovered that a race condition existed in the Bluetooth subsystem in the Linux kernel when modifying certain settings values through debugfs. A privileged local attacker could use this to cause a denial of service. (CVE-2024-24857, CVE-2024-24858, CVE-2024-24859)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Compute Acceleration Framework; - Accessibility subsystem; - Android drivers; - Drivers core; - Bluetooth drivers; - Clock framework and drivers; - Data acquisition framework and drivers; - Cryptographic API; - Buffer Sharing and Synchronization framework; - GPU drivers; - On-Chip Interconnect management framework; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - VMware VMCI Driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - Device tree and open firmware driver; - Chrome hardware platform drivers; - i.MX PM domains; - TI SCI PM domains driver; - S/390 drivers; - SCSI drivers; - SPI subsystem; - Thermal drivers; - TTY drivers; - USB subsystem; - Framebuffer layer; - BTRFS file system; - Network file system server daemon; - NILFS2 file system; - File systems infrastructure; - Pstore file system; - SMB…

Most recent entries from all

CVE-2024-35871 — riscv: process: Fix kernel gp leakage

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities