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