Amazon Linux 2 : kernel (ALAS-2021-1636)

high Nessus Plugin ID 149870

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Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of kernel installed on the remote host is prior to 4.14.232-176.381. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2021-1636 advisory.

2024-05-23: CVE-2021-46909 was added to this advisory.

2024-05-23: CVE-2021-46974 was added to this advisory.

2024-03-13: CVE-2021-46905 was added to this advisory.

2024-03-13: CVE-2021-46904 was added to this advisory.

2024-03-13: CVE-2021-46915 was added to this advisory.

An issue was discovered in the Linux kernel related to mm/gup.c and mm/huge_memory.c. The get_user_pages (aka gup) implementation, when used for a copy-on-write page, does not properly consider the semantics of read operations and therefore can grant unintended read access. (CVE-2020-29374)

A use-after-free flaw was found in the Linux kernel's SCTP socket functionality that triggers a race condition. This flaw allows a local user to escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. (CVE-2021-23133)

A vulnerability was discovered in retrieve_ptr_limit in kernel/bpf/verifier.c in the Linux kernel mechanism to mitigate speculatively out-of-bounds loads (Spectre mitigation). In this flaw 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. This can be abused to extract contents of kernel memory via side-channel. (CVE-2021-29155)

A flaw was found in the Linux kernel's eBPF verification code. By default, accessing the eBPF verifier is only accessible to privileged users with CAP_SYS_ADMIN. This flaw allows a local user who can insert eBPF instructions, to use the eBPF verifier to abuse a spectre-like flaw and infer all system memory. The highest threat from this vulnerability is to confidentiality. (CVE-2021-31829)

In the Linux kernel, the following vulnerability has been resolved:

net: hso: fix null-ptr-deref during tty device unregistration

Multiple ttys try to claim the same the minor number causing a doubleunregistration of the same device.
The first unregistration succeedsbut the next one results in a null-ptr-deref.

The get_free_serial_index() function returns an available minor numberbut doesn't assign it immediately.
The assignment is done by the callerlater. But before this assignment, calls to get_free_serial_index()would return the same minor number.

Fix this by modifying get_free_serial_index to assign the minor numberimmediately after one is found to be and rename it to obtain_minor()to better reflect what it does. Similary, rename set_serial_by_index()to release_minor() and modify it to free up the minor number of thegiven hso_serial. Every obtain_minor() should have correspondingrelease_minor() call. (CVE-2021-46904)

In the Linux kernel, the following vulnerability has been resolved:

net: hso: fix NULL-deref on disconnect regression

Commit 8a12f8836145 (net: hso: fix null-ptr-deref during tty deviceunregistration) fixed the racy minor allocation reported by syzbot, butintroduced an unconditional NULL-pointer dereference on every disconnectinstead.

Specifically, the serial device table must no longer be accessed afterthe minor has been released by hso_serial_tty_unregister(). (CVE-2021-46905)

In the Linux kernel, the following vulnerability has been resolved:

ARM: footbridge: fix PCI interrupt mapping (CVE-2021-46909)

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_limit: avoid possible divide error in nft_limit_init

div_u64() divides u64 by u32.

nft_limit_init() wants to divide u64 by u64, use the appropriatemath function (div64_u64)

divide error: 0000 [#1] PREEMPT SMP KASANCPU: 1 PID: 8390 Comm: syz-executor188 Not tainted 5.12.0-rc4-syzkaller #0Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011RIP: 0010:div_u64_rem include/linux/math64.h:28 [inline]RIP: 0010:div_u64 include/linux/math64.h:127 [inline]RIP: 0010:nft_limit_init+0x2a2/0x5e0 net/netfilter/nft_limit.c:85Code:
ef 4c 01 eb 41 0f 92 c7 48 89 de e8 38 a5 22 fa 4d 85 ff 0f 85 97 02 00 00 e8 ea 9e 22 fa 4c 0f af f3 45 89 ed 31 d2 4c 89 f0 <49> f7 f5 49 89 c6 e8 d3 9e 22 fa 48 8d 7d 48 48 b8 00 00 00 00 00RSP:
0018:ffffc90009447198 EFLAGS: 00010246RAX: 0000000000000000 RBX: 0000200000000000 RCX:
0000000000000000RDX: 0000000000000000 RSI: ffffffff875152e6 RDI: 0000000000000003RBP: ffff888020f80908 R08: 0000200000000000 R09: 0000000000000000R10: ffffffff875152d8 R11: 0000000000000000 R12:
ffffc90009447270R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000FS:
000000000097a300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033CR2: 00000000200001c4 CR3: 0000000026a52000 CR4: 00000000001506e0DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400Call Trace:nf_tables_newexpr net/netfilter/nf_tables_api.c:2675 [inline]nft_expr_init+0x145/0x2d0 net/netfilter/nf_tables_api.c:2713nft_set_elem_expr_alloc+0x27/0x280 net/netfilter/nf_tables_api.c:5160nf_tables_newset+0x1997/0x3150 net/netfilter/nf_tables_api.c:4321nfnetlink_rcv_batch+0x85a/0x21b0 net/netfilter/nfnetlink.c:456nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:580 [inline]nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:598netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927sock_sendmsg_nosec net/socket.c:654 [inline]sock_sendmsg+0xcf/0x120 net/socket.c:674____sys_sendmsg+0x6e8/0x810 net/socket.c:2350___sys_sendmsg+0xf3/0x170 net/socket.c:2404__sys_sendmsg+0xe5/0x1b0 net/socket.c:2433do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46entry_SYSCALL_64_after_hwframe+0x44/0xae (CVE-2021-46915)

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix masking negation logic upon negative dst register (CVE-2021-46974)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update kernel' to update your system.

Plugin Details

Severity: High

ID: 149870

File Name: al2_ALAS-2021-1636.nasl

Version: 1.7

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 5/24/2021

Updated: 5/27/2024

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.4

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-23133

CVSS v3

Risk Factor: High

Base Score: 7

Temporal Score: 6.3

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:perf, p-cpe:/a:amazon:linux:perf-debuginfo, p-cpe:/a:amazon:linux:kernel-tools-debuginfo, p-cpe:/a:amazon:linux:kernel-debuginfo-common-aarch64, p-cpe:/a:amazon:linux:kernel-tools, p-cpe:/a:amazon:linux:kernel-livepatch-4.14.232-176.381, p-cpe:/a:amazon:linux:kernel-devel, p-cpe:/a:amazon:linux:python-perf-debuginfo, p-cpe:/a:amazon:linux:kernel, p-cpe:/a:amazon:linux:kernel-debuginfo, p-cpe:/a:amazon:linux:kernel-headers, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:kernel-tools-devel, p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64, p-cpe:/a:amazon:linux:python-perf

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 5/20/2021

Vulnerability Publication Date: 11/28/2020

Reference Information

CVE: CVE-2020-29374, CVE-2021-23133, CVE-2021-29155, CVE-2021-31829, CVE-2021-46904, CVE-2021-46905, CVE-2021-46909, CVE-2021-46915, CVE-2021-46974

ALAS: 2021-1636

Detections

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