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<define-tag description>LTS security update</define-tag>
<define-tag moreinfo>
<p>Several vulnerabilities have been discovered in the Linux kernel that
may lead to the execution of arbitrary code, privilege escalation,
denial of service, or information leaks.</p>
<p>This update is not yet available for the armel (ARM EABI soft-float)
architecture.</p>
<ul>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-24586">CVE-2020-24586</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2020-24587">CVE-2020-24587</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2020-26147">CVE-2020-26147</a>
<p>Mathy Vanhoef discovered that many Wi-Fi implementations,
including Linux's mac80211, did not correctly implement reassembly
of fragmented packets. In some circumstances, an attacker within
range of a network could exploit these flaws to forge arbitrary
packets and/or to access sensitive data on that network.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-24588">CVE-2020-24588</a>
<p>Mathy Vanhoef discovered that most Wi-Fi implementations,
including Linux's mac80211, did not authenticate the <q>is
aggregated</q> packet header flag. An attacker within range of a
network could exploit this to forge arbitrary packets on that
network.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-25670">CVE-2020-25670</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2020-25671">CVE-2020-25671</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2021-23134">CVE-2021-23134</a>
<p>kiyin (尹亮) of TenCent discovered several reference counting bugs
in the NFC LLCP implementation which could lead to use-after-free.
A local user could exploit these for denial of service (crash or
memory corruption) or possibly for privilege escalation.</p>
<p>Nadav Markus and Or Cohen of Palo Alto Networks discovered that
the original fixes for these introduced a new bug that could
result in use-after-free and double-free. This has also been
fixed.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-25672">CVE-2020-25672</a>
<p>kiyin (尹亮) of TenCent discovered a memory leak in the NFC LLCP
implementation. A local user could exploit this for denial of
service (memory exhaustion).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-26139">CVE-2020-26139</a>
<p>Mathy Vanhoef discovered that a bug in some Wi-Fi implementations,
including Linux's mac80211. When operating in AP mode, they would
forward EAPOL frames from one client to another while the sender
was not yet authenticated. An attacker within range of a network
could use this for denial of service or as an aid to exploiting
other vulnerabilities.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-26558">CVE-2020-26558</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2021-0129">CVE-2021-0129</a>
<p>Researchers at ANSSI discovered vulnerabilities in the Bluetooth
Passkey authentication method, and in Linux's implementation of
it. An attacker within range of two Bluetooth devices while they
pair using Passkey authentication could exploit this to obtain the
shared secret (Passkey) and then impersonate either of the devices
to each other.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-29374">CVE-2020-29374</a>
<p>Jann Horn of Google reported a flaw in Linux's virtual memory
management. A parent and child process initially share all their
memory, but when either writes to a shared page, the page is
duplicated and unshared (copy-on-write). However, in case an
operation such as vmsplice() required the kernel to take an
additional reference to a shared page, and a copy-on-write occurs
during this operation, the kernel might have accessed the wrong
process's memory. For some programs, this could lead to an
information leak or data corruption.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2020-36322">CVE-2020-36322</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2021-28950">CVE-2021-28950</a>
<p>The syzbot tool found that the FUSE (filesystem-in-user-space)
implementation did not correctly handle a FUSE server returning
invalid attributes for a file. A local user permitted to run a
FUSE server could use this to cause a denial of service (crash).</p>
<p>The original fix for this introduced a different potential denial
of service (infinite loop in kernel space), which has also been
fixed.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-3428">CVE-2021-3428</a>
<p>Wolfgang Frisch reported a potential integer overflow in the ext4
filesystem driver. A user permitted to mount arbitrary filesystem
images could use this to cause a denial of service (crash).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-3483">CVE-2021-3483</a>
<p>马哲宇 (Zheyu Ma) reported a bug in the <q>nosy</q> driver for TI
PCILynx FireWire controllers, which could lead to list corruption
and a use-after-free. On a system that uses this driver, local
users granted access to /dev/nosy could exploit this to cause a
denial of service (crash or memory corruption) or possibly for
privilege escalation.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-3564">CVE-2021-3564</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2021-3573">CVE-2021-3573</a>, <a href="https://security-tracker.debian.org/tracker/CVE-2021-32399">CVE-2021-32399</a>
<p>The BlockSec team discovered several race conditions in the
Bluetooth subsystem that could lead to a use-after-free or
double-free. A local user could exploit these to caue a denial of
service (crash or memory corruption) or possibly for privilege
escalation.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-3587">CVE-2021-3587</a>
<p>Active Defense Lab of Venustech discovered a potential null
pointer dereference in the NFC LLCP implementation. A local user
could use this to cause a denial of service (crash).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-20292">CVE-2021-20292</a>
<p>It was discovered that the TTM buffer allocation API used by GPU
drivers did not handle allocation failures in the way that most
drivers expected, resulting in a double-free on failure. A local
user on a system using one of these drivers could possibly exploit
this to cause a denial of service (crash or memory corruption) or
for privilege escalation. The API has been changed to match
driver expectations.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-23133">CVE-2021-23133</a>
<p>Or Cohen of Palo Alto Networks discovered a race condition in the
SCTP implementation, which can lead to list corruption. A local
user could exploit this to cause a denial of service (crash or
memory corruption) or possibly for privilege escalation.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-28660">CVE-2021-28660</a>
<p>It was discovered that the rtl8188eu WiFi driver did not correctly
limit the length of SSIDs copied into scan results. An attacker
within WiFi range could use this to cause a denial of service
(crash or memory corruption) or possibly to execute code on a
vulnerable system.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-28688">CVE-2021-28688</a> (<a href="https://xenbits.xen.org/xsa/advisory-371.html">XSA-371</a>)
<p>It was discovered that the original fix for <a href="https://security-tracker.debian.org/tracker/CVE-2021-26930">CVE-2021-26930</a>
(<a href="https://xenbits.xen.org/xsa/advisory-365.html">XSA-365</a>) introduced a potential resource leak. A malicious guest
could presumably exploit this to cause a denial of service
(resource exhaustion) within the host.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-28964">CVE-2021-28964</a>
<p>Zygo Blaxell reported a race condition in the Btrfs driver which
can lead to an assertion failure. On systems using Btrfs, a local
user could exploit this to cause a denial of service (crash).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-28971">CVE-2021-28971</a>
<p>Vince Weaver reported a bug in the performance event handler for
Intel PEBS. A workaround for a hardware bug on Intel CPUs
codenamed <q>Haswell</q> and earlier could lead to a null pointer
dereference. On systems with the affected CPUs, if users are
permitted to access performance events, a local user may exploit
this to cause a denial of service (crash).</p>
<p>By default, unprivileged users do not have access to performance
events, which mitigates this issue. This is controlled by the
kernel.perf_event_paranoid sysctl.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-29154">CVE-2021-29154</a>
<p>It was discovered that the Extended BPF (eBPF) JIT compiler
for x86_64 generated incorrect branch instructions in some
cases. On systems where eBPF JIT is enabled, users could
exploit this to execute arbitrary code in the kernel.</p>
<p>By default, eBPF JIT is disabled, mitigating this issue. This is
controlled by the net.core.bpf_jit_enable sysctl.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-29265">CVE-2021-29265</a>
<p>The syzbot tool found a race condition in the USB/IP host
(server) implementation which can lead to a null pointer
dereference. On a system acting as a USB/IP host, a client
can exploit this to cause a denial of service (crash).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-29647">CVE-2021-29647</a>
<p>The syzbot tool found an information leak in the Qualcomm IPC
Router (qrtr) implementation.</p>
<p>This protocol is not enabled in Debian's official kernel
configurations.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-29650">CVE-2021-29650</a>
<p>It was discovered that a data race in the netfilter subsystem
could lead to a null pointer dereference during replacement of a
table. A local user with CAP_NET_ADMIN capability in any user
namespace could use this to cause a denial of service (crash).</p>
<p>By default, unprivileged users cannot create user namespaces,
which mitigates this issue. This is controlled by the
kernel.unprivileged_userns_clone sysctl.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-30002">CVE-2021-30002</a>
<p>Arnd Bergmann and the syzbot tool found a memory leak in the
Video4Linux (v4l) subsystem. A local user permitted to access
video devices (by default, any member of the <q>video</q> group) could
exploit this to cause a denial of service (memory exhaustion).</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-31916">CVE-2021-31916</a>
<p>Dan Carpenter reported incorrect parameter validation in the
device-mapper (dm) subsystem, which could lead to a heap buffer
overrun. However, only users with CAP_SYS_ADMIN capability
(i.e. root-equivalent) could trigger this bug, so it did not
have any security impact in this kernel version.</p></li>
<li><a href="https://security-tracker.debian.org/tracker/CVE-2021-33034">CVE-2021-33034</a>
<p>The syzbot tool found a bug in the Bluetooth subsystem that could
lead to a use-after-free. A local user could use this to cause a
denial of service (crash or memory corruption) or possibly for
privilege escalation.</p></li>
</ul>
<p>For Debian 9 stretch, these problems have been fixed in version
4.9.272-1. This update additionally includes many more bug fixes from
stable updates 4.9.259-4.9.272 inclusive.</p>
<p>We recommend that you upgrade your linux packages.</p>
<p>For the detailed security status of linux please refer to
its security tracker page at:
<a href="https://security-tracker.debian.org/tracker/linux">https://security-tracker.debian.org/tracker/linux</a></p>
<p>Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: <a href="https://wiki.debian.org/LTS">https://wiki.debian.org/LTS</a></p>
</define-tag>
# do not modify the following line
#include "$(ENGLISHDIR)/lts/security/2021/dla-2689.data"
# $Id: $
|
