NULL pointer dereference in Linux kernel - CVE-2021-4095
Published: January 20, 2022
Vulnerability identifier: #VU59895
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-4095
CWE-ID: CWE-476
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to perform a denial of service (DoS) attack.
The vulnerability exists due to a NULL pointer dereference error within the Linux kernel's KVM when dirty ring logging is enabled without an active vCPU context in kvm_dirty_ring_get() function in virt/kvm/dirty_ring.c. A local user can pass specially crafted input to the KVM_XEN_HVM_SET_ATTR IOCTL and perform a denial of service (DoS) attack.
Affected software
Linux kernel
Fedora
kernel
kernel-headers
kernel-tools
Fedora
kernel
kernel-headers
kernel-tools
How to mitigate CVE-2021-4095
Install updates from vendor's website.
kernel - addressed in versions 5.17.4-100.fc34, 5.17.4-200.fc35
kernel-headers - addressed in versions 5.17.4-100.fc34, 5.17.4-200.fc35
kernel-tools - addressed in versions 5.17.4-100.fc34, 5.17.4-200.fc35
kernel-headers - addressed in versions 5.17.4-100.fc34, 5.17.4-200.fc35
kernel-tools - addressed in versions 5.17.4-100.fc34, 5.17.4-200.fc35