SB2021041393 - Ubuntu update for linux

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Heap-based buffer overflow (CVE-ID: CVE-2021-20194)

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

The vulnerability exists due to a boundary error within the __cgroup_bpf_run_filter_getsockopt() function, when kernel is compiled with config params CONFIG_BPF_SYSCALL=y , CONFIG_BPF=y , CONFIG_CGROUPS=y , CONFIG_CGROUP_BPF=y , CONFIG_HARDENED_USERCOPY not set, and BPF hook to getsockopt is registered. A local user can trigger a heap-based buffer overflow and execute arbitrary code with elevated privileges.

2) Resource management error (CVE-ID: CVE-2021-26930)

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper management of internal resources when processing service requests to the PV backend within drivers/block/xen-blkback/blkback.c driver in Xen. A local user on the guest OS can perform a denial of service (DoS) attack.

3) Allocation of resources without limits or throttling (CVE-ID: CVE-2021-26931)

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to allocation of resources without limits or throttling error within the scsiback_gnttab_data_map_batch() function in drivers/xen/xen-scsiback.c. A local user can perform a denial of service (DoS) attack.

4) Use-after-free (CVE-ID: CVE-2021-3348)

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

The vulnerability exists due to a use-after-free error within the nbd_add_socket in drivers/block/nbd.c. A local authenticated user can trigger a use-after-free error and escalate privileges on the system.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-4909-1