Debian Security Advisory

DLA-2785-1 linux-4.19 -- LTS security update

Date Reported:
15 Oct 2021
Affected Packages:
linux-4.19
Vulnerable:
Yes
Security database references:
In Mitre's CVE dictionary: CVE-2020-3702, CVE-2020-16119, CVE-2021-3444, CVE-2021-3600, CVE-2021-3612, CVE-2021-3653, CVE-2021-3655, CVE-2021-3656, CVE-2021-3679, CVE-2021-3732, CVE-2021-3743, CVE-2021-3753, CVE-2021-22543, CVE-2021-33624, CVE-2021-34556, CVE-2021-35039, CVE-2021-35477, CVE-2021-37159, CVE-2021-38160, CVE-2021-38198, CVE-2021-38199, CVE-2021-38205, CVE-2021-40490.
More information:

Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or information leaks.

  • CVE-2020-3702

    A flaw was found in the driver for Atheros IEEE 802.11n family of chipsets (ath9k) allowing information disclosure.

  • CVE-2020-16119

    Hadar Manor reported a use-after-free in the DCCP protocol implementation in the Linux kernel. A local attacker can take advantage of this flaw to cause a denial of service or potentially to execute arbitrary code.

  • CVE-2021-3444

    , CVE-2021-3600

    Two flaws were discovered in the Extended BPF (eBPF) verifier. A local user could exploit these to read and write arbitrary memory in the kernel, which could be used for privilege escalation.

    This can be mitigated by setting sysctl kernel.unprivileged_bpf_disabled=1, which disables eBPF use by unprivileged users.

  • CVE-2021-3612

    Murray McAllister reported a flaw in the joystick input subsystem. A local user permitted to access a joystick device could exploit this to read and write out-of-bounds in the kernel, which could be used for privilege escalation.

  • CVE-2021-3653

    Maxim Levitsky discovered a vulnerability in the KVM hypervisor implementation for AMD processors in the Linux kernel: Missing validation of the `int_ctl` VMCB field could allow a malicious L1 guest to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. The L2 guest can take advantage of this flaw to write to a limited but still relatively large subset of the host physical memory.

  • CVE-2021-3655

    Ilja Van Sprundel and Marcelo Ricardo Leitner found multiple flaws in the SCTP implementation, where missing validation could lead to an out-of-bounds read. On a system using SCTP, a networked attacker could exploit these to cause a denial of service (crash).

  • CVE-2021-3656

    Maxim Levitsky and Paolo Bonzini discovered a flaw in the KVM hypervisor implementation for AMD processors in the Linux kernel. Missing validation of the `virt_ext` VMCB field could allow a malicious L1 guest to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) for the L2 guest. Under these circumstances, the L2 guest is able to run VMLOAD/VMSAVE unintercepted and thus read/write portions of the host's physical memory.

  • CVE-2021-3679

    A flaw in the Linux kernel tracing module functionality could allow a privileged local user (with CAP_SYS_ADMIN capability) to cause a denial of service (resource starvation).

  • CVE-2021-3732

    Alois Wohlschlager reported a flaw in the implementation of the overlayfs subsystem, allowing a local attacker with privileges to mount a filesystem to reveal files hidden in the original mount.

  • CVE-2021-3743

    An out-of-bounds memory read was discovered in the Qualcomm IPC router protocol implementation, allowing to cause a denial of service or information leak.

  • CVE-2021-3753

    Minh Yuan reported a race condition in the vt_k_ioctl in drivers/tty/vt/vt_ioctl.c, which may cause an out of bounds read in vt.

  • CVE-2021-22543

    David Stevens discovered a flaw in how the KVM hypervisor maps host memory into a guest. A local user permitted to access /dev/kvm could use this to cause certain pages to be freed when they should not, leading to a use-after-free. This could be used to cause a denial of service (crash or memory corruption) or possibly for privilege escalation.

  • CVE-2021-33624

    , CVE-2021-34556, CVE-2021-35477

    Multiple researchers discovered flaws in the Extended BPF (eBPF) verifier's protections against information leaks through speculation execution. A local user could exploit these to read sensitive information.

    This can be mitigated by setting sysctl kernel.unprivileged_bpf_disabled=1, which disables eBPF use by unprivileged users.

  • CVE-2021-35039

    A flaw was discovered in module signature enforcement. A custom kernel with IMA enabled might have allowed loading unsigned kernel modules when it should not have.

  • CVE-2021-37159

    A flaw was discovered in the hso driver for Option mobile broadband modems. An error during initialisation could lead to a double-free or use-after-free. An attacker able to plug in USB devices could use this to cause a denial of service (crash or memory corruption) or possibly to run arbitrary code.

  • CVE-2021-38160

    A flaw in the virtio_console was discovered allowing data corruption or data loss by an untrusted device.

  • CVE-2021-38198

    A flaw was discovered in the KVM implementation for x86 processors, that could result in virtual memory protection within a guest not being applied correctly. When shadow page tables are used - i.e. for nested virtualisation, or on CPUs lacking the EPT or NPT feature - a user of the guest OS might be able to exploit this for denial of service or privilege escalation within the guest.

  • CVE-2021-38199

    Michael Wakabayashi reported a flaw in the NFSv4 client implementation, where incorrect connection setup ordering allows operations of a remote NFSv4 server to cause a denial of service.

  • CVE-2021-38205

    An information leak was discovered in the xilinx_emaclite network driver. On a custom kernel where this driver is enabled and used, this might make it easier to exploit other kernel bugs.

  • CVE-2021-40490

    A race condition was discovered in the ext4 subsystem when writing to an inline_data file while its xattrs are changing. This could result in denial of service.

For Debian 9 stretch, these problems have been fixed in version 4.19.208-1~deb9u1.

We recommend that you upgrade your linux-4.19 packages.

For the detailed security status of linux-4.19 please refer to its security tracker page at: https://security-tracker.debian.org/tracker/linux-4.19

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