Debian Security Advisory

DLA-2689-1 linux -- LTS security update

Date Reported:
22 Jun 2021
Affected Packages:
linux
Vulnerable:
Yes
Security database references:
In Mitre's CVE dictionary: CVE-2020-24586, CVE-2020-24587, CVE-2020-24588, CVE-2020-25670, CVE-2020-25671, CVE-2020-25672, CVE-2020-26139, CVE-2020-26147, CVE-2020-26558, CVE-2020-29374, CVE-2020-36322, CVE-2021-0129, CVE-2021-3428, CVE-2021-3483, CVE-2021-3564, CVE-2021-3573, CVE-2021-3587, CVE-2021-20292, CVE-2021-23133, CVE-2021-23134, CVE-2021-28660, CVE-2021-28688, CVE-2021-28950, CVE-2021-28964, CVE-2021-28971, CVE-2021-29154, CVE-2021-29265, CVE-2021-29647, CVE-2021-29650, CVE-2021-30002, CVE-2021-31916, CVE-2021-32399, CVE-2021-33034.
More information:

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.

This update is not yet available for the armel (ARM EABI soft-float) architecture.

  • CVE-2020-24586, CVE-2020-24587, CVE-2020-26147

    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.

  • CVE-2020-24588

    Mathy Vanhoef discovered that most Wi-Fi implementations, including Linux's mac80211, did not authenticate the is aggregated packet header flag. An attacker within range of a network could exploit this to forge arbitrary packets on that network.

  • CVE-2020-25670, CVE-2020-25671, CVE-2021-23134

    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.

    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.

  • CVE-2020-25672

    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).

  • CVE-2020-26139

    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.

  • CVE-2020-26558, CVE-2021-0129

    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.

  • CVE-2020-29374

    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.

  • CVE-2020-36322, CVE-2021-28950

    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).

    The original fix for this introduced a different potential denial of service (infinite loop in kernel space), which has also been fixed.

  • CVE-2021-3428

    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).

  • CVE-2021-3483

    马哲宇 (Zheyu Ma) reported a bug in the nosy 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.

  • CVE-2021-3564, CVE-2021-3573, CVE-2021-32399

    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.

  • CVE-2021-3587

    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).

  • CVE-2021-20292

    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.

  • CVE-2021-23133

    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.

  • CVE-2021-28660

    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.

  • CVE-2021-28688 (XSA-371)

    It was discovered that the original fix for CVE-2021-26930 (XSA-365) introduced a potential resource leak. A malicious guest could presumably exploit this to cause a denial of service (resource exhaustion) within the host.

  • CVE-2021-28964

    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).

  • CVE-2021-28971

    Vince Weaver reported a bug in the performance event handler for Intel PEBS. A workaround for a hardware bug on Intel CPUs codenamed Haswell 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).

    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.

  • CVE-2021-29154

    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.

    By default, eBPF JIT is disabled, mitigating this issue. This is controlled by the net.core.bpf_jit_enable sysctl.

  • CVE-2021-29265

    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).

  • CVE-2021-29647

    The syzbot tool found an information leak in the Qualcomm IPC Router (qrtr) implementation.

    This protocol is not enabled in Debian's official kernel configurations.

  • CVE-2021-29650

    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).

    By default, unprivileged users cannot create user namespaces, which mitigates this issue. This is controlled by the kernel.unprivileged_userns_clone sysctl.

  • CVE-2021-30002

    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 video group) could exploit this to cause a denial of service (memory exhaustion).

  • CVE-2021-31916

    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.

  • CVE-2021-33034

    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.

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.

We recommend that you upgrade your linux packages.

For the detailed security status of linux please refer to its security tracker page at: https://security-tracker.debian.org/tracker/linux

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS