CVE-2021-28691

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

This kernel update is based on upstream 5.10.43 and fixes at least the following security issues:

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that received fragments be cleared from memory after (re)connecting to a network. Under the right circumstances, when another device sends fragmented frames encrypted using WEP, CCMP, or GCMP, this can be abused to inject arbitrary network packets and/or exfiltrate user data (CVE-2020-24586).

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that all fragments of a frame are encrypted under the same key. An adversary can abuse this to decrypt selected fragments when another device sends fragmented frames and the WEP, CCMP, or GCMP encryption key is periodically renewed (CVE-2020-24587).

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that the A-MSDU flag in the plaintext QoS header field is authenticated. Against devices that support receiving non-SSP A-MSDU frames (which is mandatory as part of 802.11n), an adversary can abuse this to inject arbitrary network packets (CVE-2020-24588).

An issue was discovered in the kernel. An Access Point (AP) forwards EAPOL frames to other clients even though the sender has not yet successfully authenticated to the AP. This might be abused in projected Wi-Fi networks to launch denial-of-service attacks against connected clients and makes it easier to exploit other vulnerabilities in connected clients (CVE-2020-26139).

An issue was discovered in the kernel ath10k driver. The Wi-Fi implementation does not verify the Message Integrity Check (authenticity) of fragmented TKIP frames. An adversary can abuse this to inject and possibly decrypt packets in WPA or WPA2 networks that support the TKIP data-confidentiality protocol (CVE-2020-26141).

An issue was discovered in the kernel ath10k driver. The WEP, WPA, WPA2, and WPA3 implementations accept second (or subsequent) broadcast fragments even when sent in plaintext and process them as full unfragmented frames. An adversary can abuse this to inject arbitrary network packets independent of the network configuration (CVE-2020-26145).

An issue was discovered in the Linux kernel 5.8.9. The WEP, WPA, WPA2, and WPA3 implementations reassemble fragments even though some of them were sent in plaintext. This vulnerability can be abused to inject packets and/ or exfiltrate selected fragments when another device sends fragmented frames and the WEP, CCMP, or GCMP data-confidentiality protocol is used (CVE-2020-26147).

A use after free vulnerability has been found in the hci_sock_bound_ioctl() function of the Linux kernel. It can allow attackers to corrupt kernel heaps (kmalloc-8k to be specific) and adopt further exploitations (CVE-2021-3573).

There is a guest triggered use-after-free in Linux xen-netback. A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer. A malicious or buggy frontend driver can trigger a dom0 crash. Privilege escalation and information leaks cannot be ruled out. (CVE-2021-28691 / XSA-374).

There is a null pointer dereference in llcp_sock_getname in net/nfc/ llcp_sock.c of the Linux kernel. An unprivileged user can trigger this bug and cause denial of service (CVE-2021-38208).

Other fixes in this update:

• bpf: Forbid trampoline attach for functions with variable arguments
• bpf: Add deny list of btf ids check for tracing programs -…

This kernel-linus update is based on upstream 5.10.43 and fixes at least the following security issues:

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that received fragments be cleared from memory after (re)connecting to a network. Under the right circumstances, when another device sends fragmented frames encrypted using WEP, CCMP, or GCMP, this can be abused to inject arbitrary network packets and/or exfiltrate user data (CVE-2020-24586).

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that all fragments of a frame are encrypted under the same key. An adversary can abuse this to decrypt selected fragments when another device sends fragmented frames and the WEP, CCMP, or GCMP encryption key is periodically renewed (CVE-2020-24587).

The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that the A-MSDU flag in the plaintext QoS header field is authenticated. Against devices that support receiving non-SSP A-MSDU frames (which is mandatory as part of 802.11n), an adversary can abuse this to inject arbitrary network packets (CVE-2020-24588).

An issue was discovered in the kernel. An Access Point (AP) forwards EAPOL frames to other clients even though the sender has not yet successfully authenticated to the AP. This might be abused in projected Wi-Fi networks to launch denial-of-service attacks against connected clients and makes it easier to exploit other vulnerabilities in connected clients (CVE-2020-26139).

An issue was discovered in the kernel ath10k driver. The Wi-Fi implementation does not verify the Message Integrity Check (authenticity) of fragmented TKIP frames. An adversary can abuse this to inject and possibly decrypt packets in WPA or WPA2 networks that support the TKIP data-confidentiality protocol (CVE-2020-26141).

An issue was discovered in the kernel ath10k driver. The WEP, WPA, WPA2, and WPA3 implementations accept second (or subsequent) broadcast fragments even when sent in plaintext and process them as full unfragmented frames. An adversary can abuse this to inject arbitrary network packets independent of the network configuration (CVE-2020-26145).

An issue was discovered in the Linux kernel 5.8.9. The WEP, WPA, WPA2, and WPA3 implementations reassemble fragments even though some of them were sent in plaintext. This vulnerability can be abused to inject packets and/ or exfiltrate selected fragments when another device sends fragmented frames and the WEP, CCMP, or GCMP data-confidentiality protocol is used (CVE-2020-26147).

A double-free memory corruption in the Linux kernel HCI device initialization subsystem was found in the way user attach malicious HCI TTY Bluetooth device. A local user could use this flaw to crash the system (CVE-2021-3564).

A use after free vulnerability has been found in the hci_sock_bound_ioctl() function of the Linux kernel. It can allow attackers to corrupt kernel heaps (kmalloc-8k to be specific) and adopt further exploitations (CVE-2021-3573).

There is a guest triggered use-after-free in Linux xen-netback. A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer. A malicious or buggy frontend driver can trigger a dom0 crash. Privilege escalation and information leaks cannot be ruled out. (CVE-2021-28691 / XSA-374).

There is a null pointer dereference in llcp_sock_getname in net/nfc/ llcp_sock.c of the Linux kernel. An unprivileged…

It was discovered that the virtual file system implementation in the Linux kernel contained an unsigned to signed integer conversion error. A local attacker could use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2021-33909)

Michael Brown discovered that the Xen netback driver in the Linux kernel did not properly handle malformed packets from a network PV frontend, leading to a use-after-free vulnerability. An attacker in a guest VM could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-28691)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device initialization failure, leading to a double-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3564)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device detach events, leading to a use-after-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3573)

It was discovered that the NFC implementation in the Linux kernel did not properly handle failed connect events leading to a NULL pointer dereference. A local attacker could use this to cause a denial of service. (CVE-2021-3587)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly perform access control. An authenticated attacker could possibly use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Michael Brown discovered that the Xen netback driver in the Linux kernel did not properly handle malformed packets from a network PV frontend, leading to a use-after-free vulnerability. An attacker in a guest VM could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-28691)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device initialization failure, leading to a double-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3564)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device detach events, leading to a use-after-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3573)

It was discovered that the NFC implementation in the Linux kernel did not properly handle failed connect events leading to a NULL pointer dereference. A local attacker could use this to cause a denial of service. (CVE-2021-3587)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly perform access control. An authenticated attacker could possibly use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Michael Brown discovered that the Xen netback driver in the Linux kernel did not properly handle malformed packets from a network PV frontend, leading to a use-after-free vulnerability. An attacker in a guest VM could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-28691)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device initialization failure, leading to a double-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3564)

It was discovered that the bluetooth subsystem in the Linux kernel did not properly handle HCI device detach events, leading to a use-after-free vulnerability. An attacker could use this to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3573)

It was discovered that the NFC implementation in the Linux kernel did not properly handle failed connect events leading to a NULL pointer dereference. A local attacker could use this to cause a denial of service. (CVE-2021-38208)