SB2021032324 - Ubuntu update for linux

Description

This security bulletin contains information about 6 secuirty vulnerabilities.

1) Out-of-bounds read (CVE-ID: CVE-2021-3444)

The vulnerability allows a local user to execute arbitrary code.

The vulnerability exists due to an out-of-bounds read error within the fixup_bpf_calls() function in kernel/bpf/verifier.c. A local user can execute arbitrary code.

2) Buffer overflow (CVE-ID: CVE-2021-27365)

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

The vulnerability exists due to a boundary error when processing Netlink messages in Linux kernel through 5.11.3, as certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. A local unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length of a Netlink message, trigger memory corruption and execute arbitrary code on the system with elevated privileges.

3) Off-by-one (CVE-ID: CVE-2020-27171)

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to an off-by-one error in kernel/bpf/verifier.c affecting out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations. A local user can run a specially crafted program to gain access to sensitive information on the system.

4) Observable discrepancy (CVE-ID: CVE-2020-27170)

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists in kernel/bpf/verifier.c due to kernel performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations. A local user can run a specially crafted program to gain access to sensitive information.

5) Information disclosure (CVE-ID: CVE-2021-27363)

The vulnerability allows a local user to gain access to potentially sensitive information.

The vulnerability exists due to the show_transport_handle() shows iSCSI transport handle to non-root users. A local user can gain unauthorized access to sensitive information and use it along with another vulnerability, such as #VU51452, to escalate privileges on the system.

6) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2021-27364)

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

The vulnerability exists due to iscsi_if_recv_msg() allows non-root users to connect and send commands to the Linux kernel. A local user can escalate privileges on the system.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-4887-1