SB2021042179 - Fedora 34 update for kernel, kernel-headers, kernel-tools

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Race condition (CVE-ID: CVE-2021-23133)

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

The vulnerability exists due to a race condition in Linux kernel SCTP sockets (net/sctp/socket.c). If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by a local user with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket.

2) Out-of-bounds read (CVE-ID: CVE-2021-29155)

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

The vulnerability exists in retrieve_ptr_limit in kernel/bpf/verifier.c in the Linux kernel mechanism. A local, special user privileged (CAP_SYS_ADMIN) BPF program running on affected systems may bypass the protection, and execute speculatively out-of-bounds loads from the kernel memory.

Remediation

Install update from vendor's website.

References

• https://bodhi.fedoraproject.org/updates/FEDORA-2021-a963f04012