CVE-2017-16995: Debian -- Security Information -- DSA-4073-1 linux

Debian Security Advisory

Date Reported:

23 Dec 2017

Affected Packages:

linux

Vulnerable:

Yes

Security database references:

In Mitre’s CVE dictionary: CVE-2017-8824, CVE-2017-16538, CVE-2017-16644, CVE-2017-16995, CVE-2017-17448, CVE-2017-17449, CVE-2017-17450, CVE-2017-17558, CVE-2017-17712, CVE-2017-17741, CVE-2017-17805, CVE-2017-17806, CVE-2017-17807, CVE-2017-17862, CVE-2017-17863, CVE-2017-17864, CVE-2017-1000407, CVE-2017-1000410.

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-2017-8824

  Mohamed Ghannam discovered that the DCCP implementation did not correctly manage resources when a socket is disconnected and reconnected, potentially leading to a use-after-free. A local user could use this for denial of service (crash or data corruption) or possibly for privilege escalation. On systems that do not already have the dccp module loaded, this can be mitigated by disabling it: echo>> /etc/modprobe.d/disable-dccp.conf install dccp false

• CVE-2017-16538

  Andrey Konovalov reported that the dvb-usb-lmedm04 media driver did not correctly handle some error conditions during initialisation. A physically present user with a specially designed USB device can use this to cause a denial of service (crash).

• CVE-2017-16644

  Andrey Konovalov reported that the hdpvr media driver did not correctly handle some error conditions during initialisation. A physically present user with a specially designed USB device can use this to cause a denial of service (crash).

• CVE-2017-16995

  Jann Horn discovered that the Extended BPF verifier did not correctly model the behaviour of 32-bit load instructions. A local user can use this for privilege escalation.

• CVE-2017-17448

  Kevin Cernekee discovered that the netfilter subsystem allowed users with the CAP_NET_ADMIN capability in any user namespace, not just the root namespace, to enable and disable connection tracking helpers. This could lead to denial of service, violation of network security policy, or have other impact.

• CVE-2017-17449

  Kevin Cernekee discovered that the netlink subsystem allowed users with the CAP_NET_ADMIN capability in any user namespace to monitor netlink traffic in all net namespaces, not just those owned by that user namespace. This could lead to exposure of sensitive information.

• CVE-2017-17450

  Kevin Cernekee discovered that the xt_osf module allowed users with the CAP_NET_ADMIN capability in any user namespace to modify the global OS fingerprint list.

• CVE-2017-17558

  Andrey Konovalov reported that that USB core did not correctly handle some error conditions during initialisation. A physically present user with a specially designed USB device can use this to cause a denial of service (crash or memory corruption), or possibly for privilege escalation.

• CVE-2017-17712

  Mohamed Ghannam discovered a race condition in the IPv4 raw socket implementation. A local user could use this to obtain sensitive information from the kernel.

• CVE-2017-17741

  Dmitry Vyukov reported that the KVM implementation for x86 would over-read data from memory when emulating an MMIO write if the kvm_mmio tracepoint was enabled. A guest virtual machine might be able to use this to cause a denial of service (crash).

• CVE-2017-17805

  It was discovered that some implementations of the Salsa20 block cipher did not correctly handle zero-length input. A local user could use this to cause a denial of service (crash) or possibly have other security impact.

• CVE-2017-17806

  It was discovered that the HMAC implementation could be used with an underlying hash algorithm that requires a key, which was not intended. A local user could use this to cause a denial of service (crash or memory corruption), or possibly for privilege escalation.

• CVE-2017-17807

  Eric Biggers discovered that the KEYS subsystem lacked a check for write permission when adding keys to a process’s default keyring. A local user could use this to cause a denial of service or to obtain sensitive information.

• CVE-2017-17862

  Alexei Starovoitov discovered that the Extended BPF verifier ignored unreachable code, even though it would still be processed by JIT compilers. This could possibly be used by local users for denial of service. It also increases the severity of bugs in determining unreachable code.

• CVE-2017-17863

  Jann Horn discovered that the Extended BPF verifier did not correctly model pointer arithmetic on the stack frame pointer. A local user can use this for privilege escalation.

• CVE-2017-17864

  Jann Horn discovered that the Extended BPF verifier could fail to detect pointer leaks from conditional code. A local user could use this to obtain sensitive information in order to exploit other vulnerabilities.

• CVE-2017-1000407

  Andrew Honig reported that the KVM implementation for Intel processors allowed direct access to host I/O port 0x80, which is not generally safe. On some systems this allows a guest VM to cause a denial of service (crash) of the host.

• CVE-2017-1000410

  Ben Seri reported that the Bluetooth subsystem did not correctly handle short EFS information elements in L2CAP messages. An attacker able to communicate over Bluetooth could use this to obtain sensitive information from the kernel.

The various problems in the Extended BPF verifier can be mitigated by disabling use of Extended BPF by unprivileged users: sysctl kernel.unprivileged_bpf_disabled=1

Debian disables unprivileged user namespaces by default, but if they are enabled (via the kernel.unprivileged_userns_clone sysctl) then CVE-2017-17448 can be exploited by any local user.

For the stable distribution (stretch), these problems have been fixed in version 4.9.65-3+deb9u1.

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