CVE-2021-47618

Technical Description

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

ARM: 9170/1: fix panic when kasan and kprobe are enabled

arm32 uses software to simulate the instruction replaced

by kprobe. some instructions may be simulated by constructing

assembly functions. therefore, before executing instruction

simulation, it is necessary to construct assembly function

execution environment in C language through binding registers.

after kasan is enabled, the register binding relationship will

be destroyed, resulting in instruction simulation errors and

causing kernel panic.

the kprobe emulate instruction function is distributed in three

files: actions-common.c actions-arm.c actions-thumb.c, so disable

KASAN when compiling these files.

for example, use kprobe insert on cap_capable+20 after kasan

enabled, the cap_capable assembly code is as follows:

<cap_capable>:

e92d47f0 push {r4, r5, r6, r7, r8, r9, sl, lr}

e1a05000 mov r5, r0

e280006c add r0, r0, #108 ; 0x6c

e1a04001 mov r4, r1

e1a0600

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References