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Debian Security Advisory DSA-4120-1                   security@debian.org
https://www.debian.org/security/                        Yves-Alexis Perez
February 22, 2018                     https://www.debian.org/security/faq
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Package        : linux
CVE ID         : CVE-2017-5715 CVE-2017-5754 CVE-2017-13166 CVE-2018-5750

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

CVE-2017-5715

    Multiple researchers have discovered a vulnerability in various
    processors supporting speculative execution, enabling an attacker
    controlling an unprivileged process to read memory from arbitrary
    addresses, including from the kernel and all other processes running on
    the system.

    This specific attack has been named Spectre variant 2 (branch target
    injection) and is mitigated in the Linux kernel for the Intel x86-64
    architecture by using the 'retpoline' compiler feature which allows
    indirect branches to be isolated from speculative execution.

CVE-2017-5754

    Multiple researchers have discovered a vulnerability in Intel
    processors, enabling an attacker controlling an unprivileged process to
    read memory from arbitrary addresses, including from the kernel and all
    other processes running on the system.

    This specific attack has been named Meltdown and is addressed in the
    Linux kernel on the powerpc/ppc64el architectures by flushing the L1
    data cache on exit from kernel mode to user mode (or from hypervisor to
    kernel).
    
    This works on Power7, Power8 and Power9 processors.

CVE-2017-13166

    A bug in the 32-bit compatibility layer of the v4l2 IOCTL handling code
    has been found. Memory protections ensuring user-provided buffers always
    point to userland memory were disabled, allowing . This bug could be
    exploited by an attacker to overwrite kernel memory from an unprivileged
    userland process, leading to privilege escalation.

CVE-2018-5750

    An information leak has been found in the Linux kernel. The
    acpi_smbus_hc_add() prints a kernel address in the kernel log at every
    boot, which could be used by an attacker on the system to defeat kernel
    ASLR.

Additionnaly to those vulnerability, some mitigations for CVE-2017-5753 are
included in this release.

CVE-2017-5753

    Multiple researchers have discovered a vulnerability in various
    processors supporting speculative execution, enabling an attacker
    controlling an unprivileged process to read memory from arbitrary
    addresses, including from the kernel and all other processes running on
    the system.

    This specific attack has been named Spectre variant 1 (bounds-check
    bypass) and is mitigated in the Linux kernel architecture by identifying
    vulnerable code sections (array bounds checking followed by array
    access) and replacing the array access with the speculation-safe
    array_index_nospec() function.

    More use sites will be added over time.

For the stable distribution (stretch), these problems have been fixed in
version 4.9.82-1+deb9u2.

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@lists.debian.org
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