Use-after-free in Linux kernel - CVE-2021-29266

Vulnerability identifier: #VU60357

CSH Severity: Low

CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2021-29266

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error in drivers/vhost/vdpa.c, because "v->config_ctx" has an invalid value upon re-opening a character device. A local user can trigger a use-after-free error and execute arbitrary code with elevated privileges.

Linux kernel
Ubuntu
linux-image-lowlatency (Ubuntu package)
linux-image-generic-lpae (Ubuntu package)
linux-image-generic-64k (Ubuntu package)
linux-image-generic (Ubuntu package)
linux-image-oem-20.04 (Ubuntu package)
linux-image-virtual (Ubuntu package)
linux-image-5.8.0-53-generic-lpae (Ubuntu package)
linux-image-5.8.0-53-lowlatency (Ubuntu package)
linux-image-5.8.0-53-generic-64k (Ubuntu package)
linux-image-5.8.0-53-generic (Ubuntu package)
linux-image-generic-64k-hwe-20.04 (Ubuntu package)
linux-image-generic-hwe-20.04 (Ubuntu package)
linux-image-generic-lpae-hwe-20.04 (Ubuntu package)
linux-image-lowlatency-hwe-20.04 (Ubuntu package)
linux-image-virtual-hwe-20.04 (Ubuntu package)
linux-image-5.8.0-1024-raspi-nolpae (Ubuntu package)
linux-image-raspi-nolpae (Ubuntu package)
linux-image-raspi (Ubuntu package)
linux-image-5.8.0-1024-raspi (Ubuntu package)
linux-image-kvm (Ubuntu package)
linux-image-5.8.0-1027-kvm (Ubuntu package)
linux-image-oracle (Ubuntu package)
linux-image-5.8.0-1029-oracle (Ubuntu package)
linux-image-gke (Ubuntu package)
linux-image-gcp (Ubuntu package)
linux-image-5.8.0-1031-gcp (Ubuntu package)
linux-image-azure (Ubuntu package)
linux-image-5.8.0-1032-azure (Ubuntu package)
linux-image-aws (Ubuntu package)
linux-image-5.8.0-1033-aws (Ubuntu package)
linux-image-5.10.0-1026-oem (Ubuntu package)
linux-image-oem-20.04b (Ubuntu package)

Install updates from vendor's website.

Linux kernel - update to 5.11.9
linux-image-lowlatency (Ubuntu package) - update to 5.8.0.53.58
linux-image-generic-lpae (Ubuntu package) - update to 5.8.0.53.58
linux-image-generic-64k (Ubuntu package) - update to 5.8.0.53.58
linux-image-generic (Ubuntu package) - update to 5.8.0.53.58
linux-image-oem-20.04 (Ubuntu package) - update to 5.8.0.53.58
linux-image-virtual (Ubuntu package) - update to 5.8.0.53.58
linux-image-5.8.0-53-generic-lpae (Ubuntu package) - update to 5.8.0-53.60~20.04.1
linux-image-5.8.0-53-lowlatency (Ubuntu package) - update to 5.8.0-53.60~20.04.1
linux-image-5.8.0-53-generic-64k (Ubuntu package) - update to 5.8.0-53.60~20.04.1
linux-image-5.8.0-53-generic (Ubuntu package) - update to 5.8.0-53.60~20.04.1
linux-image-generic-64k-hwe-20.04 (Ubuntu package) - update to 5.8.0.53.60~20.04.37
linux-image-generic-hwe-20.04 (Ubuntu package) - update to 5.8.0.53.60~20.04.37
linux-image-generic-lpae-hwe-20.04 (Ubuntu package) - update to 5.8.0.53.60~20.04.37
linux-image-lowlatency-hwe-20.04 (Ubuntu package) - update to 5.8.0.53.60~20.04.37
linux-image-virtual-hwe-20.04 (Ubuntu package) - update to 5.8.0.53.60~20.04.37
linux-image-5.8.0-1024-raspi-nolpae (Ubuntu package) - update to 5.8.0-1024.27
linux-image-raspi-nolpae (Ubuntu package) - update to 5.8.0.1024.27
linux-image-raspi (Ubuntu package) - update to 5.8.0.1024.27
linux-image-5.8.0-1024-raspi (Ubuntu package) - update to 5.8.0-1024.27
linux-image-kvm (Ubuntu package) - update to 5.8.0.1027.29
linux-image-5.8.0-1027-kvm (Ubuntu package) - update to 5.8.0-1027.29
linux-image-oracle (Ubuntu package) - update to 5.8.0.1029.28
linux-image-5.8.0-1029-oracle (Ubuntu package) - update to 5.8.0-1029.30
linux-image-gke (Ubuntu package) - update to 5.8.0.1031.31
linux-image-gcp (Ubuntu package) - update to 5.8.0.1031.31
linux-image-5.8.0-1031-gcp (Ubuntu package) - update to 5.8.0-1031.32
linux-image-azure (Ubuntu package) - update to 5.8.0.1032.32
linux-image-5.8.0-1032-azure (Ubuntu package) - update to 5.8.0-1032.34
linux-image-aws (Ubuntu package) - update to 5.8.0.1033.35
linux-image-5.8.0-1033-aws (Ubuntu package) - update to 5.8.0-1033.35
linux-image-5.10.0-1026-oem (Ubuntu package) - update to 5.10.0-1026.27
linux-image-oem-20.04b (Ubuntu package) - update to 5.10.0.1026.27

• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.9
• https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6bbf0010ba004f5e90c7aefdebc0ee4bd3283b9
• https://security.netapp.com/advisory/ntap-20210513-0005/

• Privilege escalation in Linux kernel VDPA
• Ubuntu update for linux
• Ubuntu update for linux-oem-5.10