[IT-SecNots] [SECURITY] [DSA 4073-1] linux security update

[Ben Hutchings <benh AT debian.org>]

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Debian Security Advisory DSA-4073-1                   security AT debian.org
https://www.debian.org/security/                            Ben Hutchings
December 23, 2017                     https://www.debian.org/security/faq
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Package        : linux
CVE ID         : 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

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

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

Mailing list: debian-security-announce AT lists.debian.org
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