Advisories » MGASA-2019-0171

Updated kernel-tmb packages fixes security vulnerabilities

Publication date: 16 May 2019
Type: security
Affected Mageia releases : 6
CVE: CVE-2018-1128 , CVE-2018-1129 , CVE-2018-12126 , CVE-2018-12127 , CVE-2018-12130 , CVE-2018-14625 , CVE-2018-16862 , CVE-2018-16882 , CVE-2018-16884 , CVE-2018-18397 , CVE-2018-19824 , CVE-2018-19985 , CVE-2018-1000026 , CVE-2019-3701 , CVE-2019-3819 , CVE-2019-3882 , CVE-2019-7308 , CVE-2019-6974 , CVE-2019-7221 , CVE-2019-7222 , CVE-2019-9213 , CVE-2019-11091 , CVE-2019-11486 , CVE-2019-11599


This kernel update provides the upstream 4.14.119 that adds the kernel side
mitigations for the Microarchitectural Data Sampling (MDS, also called
ZombieLoad attack) vulnerabilities in Intel processors that can allow
attackers to retrieve data being processed inside a CPU. To complete the
mitigations new microcode is also needed, either by installing the
microcode-0.20190514-1.mga6 package, or get an updated bios / uefi
firmware from the motherboard vendor.

The fixed / mitigated issues are:

Modern Intel microprocessors implement hardware-level micro-optimizations
to improve the performance of writing data back to CPU caches. The write
operation is split into STA (STore Address) and STD (STore Data)
sub-operations. These sub-operations allow the processor to hand-off
address generation logic into these sub-operations for optimized writes.
Both of these sub-operations write to a shared distributed processor
structure called the 'processor store buffer'. As a result, an
unprivileged attacker could use this flaw to read private data resident
within the CPU's processor store buffer. (CVE-2018-12126)

Microprocessors use a ‘load port’ subcomponent to perform load operations
from memory or IO. During a load operation, the load port receives data
from the memory or IO subsystem and then provides the data to the CPU
registers and operations in the CPU’s pipelines. Stale load operations
results are stored in the 'load port' table until overwritten by newer
operations. Certain load-port operations triggered by an attacker can be
used to reveal data about previous stale requests leaking data back to the
attacker via a timing side-channel. (CVE-2018-12127)

A flaw was found in the implementation of the "fill buffer", a mechanism
used by modern CPUs when a cache-miss is made on L1 CPU cache. If an
attacker can generate a load operation that would create a page fault,
the execution will continue speculatively with incorrect data from the
fill buffer while the data is fetched from higher level caches. This
response time can be measured to infer data in the fill buffer.

Uncacheable memory on some microprocessors utilizing speculative execution
may allow an authenticated user to potentially enable information disclosure
via a side channel with local access. (CVE-2019-11091)

It also fixes atleast the following security issues:

Cross-hyperthread Spectre v2 mitigation is now provided by the Single
Thread Indirect Branch Predictors (STIBP) support. Note that STIBP also
requires the functionality be supported by the Intel microcode in use.

It was found that cephx authentication protocol did not verify ceph clients
correctly and was vulnerable to replay attack. Any attacker having access
to ceph cluster network who is able to sniff packets on network can use
this vulnerability to authenticate with ceph service and perform actions
allowed by ceph service (CVE-2018-1128).

A flaw was found in the way signature calculation was handled by cephx
authentication protocol. An attacker having access to ceph cluster network
who is able to alter the message payload was able to bypass signature
checks done by cephx protocol (CVE-2018-1129).

A flaw was found in the Linux Kernel where an attacker may be able to have
an uncontrolled read to kernel-memory from within a vm guest. A race
condition between connect() and close() function may allow an attacker
using the AF_VSOCK protocol to gather a 4 byte information leak or possibly
intercept or corrupt AF_VSOCK messages destined to other clients

A security flaw was found in the Linux kernel in a way that the cleancache
subsystem clears an inode after the final file truncation (removal). The
new file created with the same inode may contain leftover pages from
cleancache and the old file data instead of the new one (CVE-2018-16862).

A use-after-free issue was found in the way the Linux kernel's KVM
hypervisor processed posted interrupts when nested(=1) virtualization is
enabled. In nested_get_vmcs12_pages(), in case of an error while
processing posted interrupt address, it unmaps the 'pi_desc_page' without
resetting 'pi_desc' descriptor address, which is later used in
pi_test_and_clear_on(). A guest user/process could use this flaw to crash
the host kernel resulting in DoS or potentially gain privileged access to
a system (CVE-2018-16882).

A flaw was found in the Linux kernel's NFS41+ subsystem. NFS41+ shares
mounted in different network namespaces at the same time can make
bc_svc_process() use wrong back-channel IDs and cause a use-after-free
vulnerability. Thus a malicious container user can cause a host kernel
memory corruption and a system panic. Due to the nature of the flaw,
privilege escalation cannot be fully ruled out (CVE-2018-16884).

The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles
access control for certain UFFDIO_ ioctl calls, as demonstrated by allowing
local users to write data into holes in a tmpfs file (if the user has
read-only access to that file, and that file contains holes)

In the Linux kernel through 4.19.6, a local user could exploit a
use-after-free in the ALSA driver by supplying a malicious USB Sound device
(with zero interfaces) (CVE-2018-19824).

A flaw was found in the Linux kernel in the function hso_probe() which
reads if_num value from the USB device (as an u8) and uses it without a
length check to index an array, resulting in an OOB memory read in
hso_probe() or hso_get_config_data(). An attacker with a forged USB
device and physical access to a system (needed to connect such a device)
can cause a system crash and a denial of service (CVE-2018-19985).

Linux Linux kernel version at least v4.8 onwards, probably well before
contains a Insufficient input validation vulnerability in bnx2x network
card driver that can result in DoS: Network card firmware assertion takes
card off-line. This attack appear to be exploitable via An attacker on a
must pass a very large, specially crafted packet to the bnx2x card.
This can be done from an untrusted guest VM (CVE-2018-1000026)

An issue was discovered in can_can_gw_rcv in net/can/gw.c in the Linux
kernel through 4.19.13. The CAN frame modification rules allow bitwise
logical operations that can be also applied to the can_dlc field. Because
of a missing check, the CAN drivers may write arbitrary content beyond
the data registers in the CAN controller's I/O memory when processing
can-gw manipulated outgoing frames. This is related to cgw_csum_xor_rel.
An unprivileged user can trigger a system crash (general protection fault)

A flaw was found in the Linux kernel in the function hid_debug_events_read()
in drivers/hid/hid-debug.c file which may enter an infinite loop with
certain parameters passed from a userspace. A local privileged user ("root")
can cause a system lock up and a denial of service (CVE-2019-3819).
A flaw was found in the Linux kernel's vfio interface implementation that
permits violation of the user's locked memory limit. If a device is bound
to a vfio driver, such as vfio-pci, and the local attacker is
administratively granted ownership of the device, it may cause a system
memory exhaustion and thus a denial of service (DoS) (CVE-2019-3882).

In the Linux kernel before 4.20.8, kvm_ioctl_create_device in
virt/kvm/kvm_main.c mishandles reference counting because of a race
condition, leading to a use-after-free (CVE-2019-6974).

A use-after-free vulnerability was found in the way the Linux kernel's KVM
hypervisor emulates a preemption timer for L2 guests when nested (=1)
virtualization is enabled. This high resolution timer(hrtimer) runs when
a L2 guest is active. After VM exit, the sync_vmcs12() timer object is
stopped. The use-after-free occurs if the timer object is freed before
calling sync_vmcs12() routine. A guest user/process could use this flaw
to crash the host kernel resulting in a denial of service or, potentially,
gain privileged access to a system (CVE-2019-7221).

An information leakage issue was found in the way Linux kernel's KVM
hypervisor handled page fault exceptions while emulating instructions
like VMXON, VMCLEAR, VMPTRLD, and VMWRITE with memory address as an
operand. It occurs if the operand is a mmio address, as the returned
exception object holds uninitialized stack memory contents. A guest
user/process could use this flaw to leak host's stack memory contents
to a guest (CVE-2019-7222).

kernel/bpf/verifier.c in the Linux kernel before 4.20.6 performs undesirable
out-of-bounds speculation on pointer arithmetic in various cases, including
cases of different branches with different state or limits to sanitize,
leading to side-channel attacks (CVE-2019-7308).

In the Linux kernel before 4.20.14, expand_downwards in mm/mmap.c lacks
a check for the mmap minimum address, which makes it easier for attackers
to exploit kernel NULL pointer dereferences on non-SMAP platforms. This is
related to a capability check for the wrong task (CVE-2019-9213).

The Siemens R3964 line discipline driver in drivers/tty/n_r3964.c in the
Linux kernel before 5.0.8 has multiple race conditions (CVE-2019-11486).

The coredump implementation in the Linux kernel before 5.0.10 does not use
locking or other mechanisms to prevent vma layout or vma flags changes while
it runs, which allows local users to obtain sensitive information, cause a
denial of service, or possibly have unspecified other impact by triggering
a race condition with mmget_not_zero or get_task_mm calls (CVE-2019-11599).

It also fixes signal handling issues causing powertop to crash and some
tracing tools to fail on execve tests.

Ndiswrapper has been updated to 1.62

WireGuard has been updated to 0.0.20190406.

For other uptstream fixes in this update, see the referenced changelogs.