cbcvebase.
CVE-2024-35871
published 2024-05-19

CVE-2024-35871: In the Linux kernel, the following vulnerability has been resolved: riscv: process: Fix kernel gp leakage childregs represents the registers which are active…

PriorityP433high7.1CVSS 3.1
AVLACLPRLUINSUCHINAH
EPSS
0.26%
18.2th percentile
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 perfectly happy to read pt_regs for user_mode_helpers before the exec completes, but gp is not one of the registers it returns. 4. PERF_SAMPLE_REGS_USER: LOCKDOWN_PERF normally prevents access to kernel addresses via PERF_SAMPLE_REGS_INTR, but due to this bug kernel addresses are also exposed via PERF_SAMPLE_REGS_USER which is permitted under LOCKDOWN_PERF. I have not attempted to write exploit code. 5. Much of the tracing infrastructure allows access to user registers. I have not attempted to determine which forms of

Affected

21 ranges
VendorProductVersion rangeFixed in
debiandebian_linux
debianlinux< linux 6.1.85-1 (bookworm)linux 6.1.85-1 (bookworm)
linuxlinux
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < 9abc3e6f1116adb7a2d4fbb8ce20c37916976bf59abc3e6f1116adb7a2d4fbb8ce20c37916976bf5
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < dff6072124f6df77bfd36951fbd88565746980efdff6072124f6df77bfd36951fbd88565746980ef
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < f6583444d7e78dae750798552b65a2519ff3ca84f6583444d7e78dae750798552b65a2519ff3ca84
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < 00effef72c98294edb1efa87ffa0f6cfb61b36a400effef72c98294edb1efa87ffa0f6cfb61b36a4
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < d8dcba0691b8e42bddb61aab201e4d918a08e5d9d8dcba0691b8e42bddb61aab201e4d918a08e5d9
linuxlinux>= 7db91e57a0acde126a162ababfb1e0ab190130cb < d14fa1fcf69db9d070e75f1c4425211fa619dfc8d14fa1fcf69db9d070e75f1c4425211fa619dfc8
linuxlinux_kernel
linuxlinux_kernel>= 0 < 5.10.216-15.10.216-1
linuxlinux_kernel>= 0 < 6.1.85-16.1.85-1
linuxlinux_kernel>= 0 < 6.8.9-16.8.9-1
linuxlinux_kernel>= 0 < 6.8.9-16.8.9-1
linuxlinux_kernel>= 0 < 5.15.0-116.1265.15.0-116.126
linuxlinux_kernel>= 0 < 6.8.0-38.386.8.0-38.38
linuxlinux_kernel>= 4.15 < 5.10.2165.10.216
linuxlinux_kernel>= 5.11 < 5.15.1545.15.154
linuxlinux_kernel>= 5.16 < 6.1.856.1.85
linuxlinux_kernel>= 6.2 < 6.6.266.6.26
linuxlinux_kernel>= 6.7 < 6.8.56.8.5

CVSS provenance

nvdv3.17.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
osv7.1HIGH
vendor_debian7.1HIGH
vendor_redhat7.1HIGH
vendor_ubuntu6.3MEDIUM
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