SB2021093033 - openEuler update for kernel

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Race condition (CVE-ID: CVE-2021-40490)

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

The vulnerability exists due to a race condition in ext4_write_inline_data_end in fs/ext4/inline.c in the ext4 subsystem in the Linux kernel. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.

2) Security restrictions bypass (CVE-ID: CVE-2021-3653)

The vulnerability allows a malicious guest to escalate privileges on the system.

The vulnerability exists due to improperly imposed security restrictions within the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest.

As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.

3) Buffer overflow (CVE-ID: CVE-2021-22543)

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

The vulnerability exists due to a boundary error in Linux kernel when handling VM_IO|VM_PFNMAP vmas in KVM. A local user can  can bypass RO checks and cause the pages to get freed while still accessible by the VMM and guest. As a result, an attacker with the ability to start and control a VM to read/write random pages of memory, can trigger memory corruption and execute arbitrary code with elevated privileges.

Remediation

Install update from vendor's website.

References

• https://www.openeuler.org/en/security/security-bulletins/detail/?id=openEuler-SA-2021-1366