Hash: SHA256

             AUSCERT External Security Bulletin Redistribution

                  linux security update for Debian 9 & 10
                              13 August 2019


        AusCERT Security Bulletin Summary

Product:           linux
Publisher:         Debian
Operating System:  Debian GNU/Linux 9
                   Debian GNU/Linux 10
Impact/Access:     Root Compromise        -- Existing Account
                   Access Privileged Data -- Existing Account
                   Denial of Service      -- Existing Account
                   Reduced Security       -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-14284 CVE-2019-14283 CVE-2019-13648
                   CVE-2019-13631 CVE-2019-10639 CVE-2019-10638
                   CVE-2019-10207 CVE-2019-3900 CVE-2019-3882
                   CVE-2019-1125 CVE-2018-20856 CVE-2018-20836
                   CVE-2018-5995 CVE-2015-8553 

Reference:         ESB-2019.1909

Original Bulletin: 

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Debian Security Advisory DSA-4497-1                   security@debian.org
https://www.debian.org/security/                            Ben Hutchings
August 13, 2019                       https://www.debian.org/security/faq
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Package        : linux
CVE ID         : CVE-2015-8553 CVE-2018-5995 CVE-2018-20836 CVE-2018-20856
                 CVE-2019-1125 CVE-2019-3882 CVE-2019-3900 CVE-2019-10207
                 CVE-2019-10638 CVE-2019-10639 CVE-2019-13631 CVE-2019-13648
                 CVE-2019-14283 CVE-2019-14284

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


    Jan Beulich discovered that CVE-2015-2150 was not completely
    addressed.  If a PCI physical function is passed through to a
    Xen guest, the guest is able to access its memory and I/O
    regions before enabling decoding of those regions.  This could
    result in a denial-of-service (unexpected NMI) on the host.

    The fix for this is incompatible with qemu versions before 2.5.

(CVE ID not yet assigned)

    Denis Andzakovic reported a missing type check in the IPv4 multicast
    routing implementation. A user with the CAP_NET_ADMIN capability (in
    any user namespace) could use this for denial-of-service (memory
    corruption or crash) or possibly for privilege escalation.


    ADLab of VenusTech discovered that the kernel logged the virtual
    addresses assigned to per-CPU data, which could make it easier to
    exploit other vulnerabilities.


    chenxiang reported a race condition in libsas, the kernel
    subsystem supporting Serial Attached SCSI (SAS) devices, which
    could lead to a use-after-free.  It is not clear how this might be


    Xiao Jin reported a potential double-free in the block subsystem,
    in case an error occurs while initialising the I/O scheduler for a
    block device.  It is not clear how this might be exploited.


    It was discovered that most x86 processors could speculatively
    skip a conditional SWAPGS instruction used when entering the
    kernel from user mode, and/or could speculatively execute it when
    it should be skipped.  This is a subtype of Spectre variant 1,
    which could allow local users to obtain sensitive information from
    the kernel or other processes.  It has been mitigated by using
    memory barriers to limit speculative execution.  Systems using an
    i386 kernel are not affected as the kernel does not use SWAPGS.


    It was found that the vfio implementation did not limit the number
    of DMA mappings to device memory.  A local user granted ownership
    of a vfio device could use this to cause a denial of service
    (out-of-memory condition).


    It was discovered that vhost drivers did not properly control the
    amount of work done to service requests from guest VMs.  A
    malicious guest could use this to cause a denial-of-service
    (unbounded CPU usage) on the host.


    The syzkaller tool found a potential null dereference in various
    drivers for UART-attached Bluetooth adapters.  A local user with
    access to a pty device or other suitable tty device could use this
    for denial-of-service (BUG/oops).


    Amit Klein and Benny Pinkas discovered that the generation of IP
    packet IDs used a weak hash function, "jhash".  This could enable
    tracking individual computers as they communicate with different
    remote servers and from different networks.  The "siphash"
    function is now used instead.


    Amit Klein and Benny Pinkas discovered that the generation of IP
    packet IDs used a weak hash function that incorporated a kernel
    virtual address.  This hash function is no longer used for IP IDs,
    although it is still used for other purposes in the network stack.


    It was discovered that the gtco driver for USB input tablets could
    overrun a stack buffer with constant data while parsing the device's
    descriptor.  A physically present user with a specially
    constructed USB device could use this to cause a denial-of-service
    (BUG/oops), or possibly for privilege escalation.


    Praveen Pandey reported that on PowerPC (ppc64el) systems without
    Transactional Memory (TM), the kernel would still attempt to
    restore TM state passed to the sigreturn() system call.  A local
    user could use this for denial-of-service (oops).


    The syzkaller tool found a missing bounds check in the floppy disk
    driver.  A local user with access to a floppy disk device, with a
    disk present, could use this to read kernel memory beyond the
    I/O buffer, possibly obtaining sensitive information.


    The syzkaller tool found a potential division-by-zero in the
    floppy disk driver.  A local user with access to a floppy disk
    device could use this for denial-of-service (oops).

(CVE ID not yet assigned)

    Denis Andzakovic reported a possible use-after-free in the
    TCP sockets implementation.  A local user could use this for
    denial-of-service (memory corruption or crash) or possibly
    for privilege escalation.

(CVE ID not yet assigned)

    The netfilter conntrack subsystem used kernel addresses as
    user-visible IDs, which could make it easier to exploit other
    security vulnerabilities.


    Julien Grall reported that Linux does not limit the amount of memory
    which a domain will attempt to baloon out, nor limits the amount of
    "foreign / grant map" memory which any individual guest can consume,
    leading to denial of service conditions (for host or guests).

For the oldstable distribution (stretch), these problems have been fixed
in version 4.9.168-1+deb9u5.

For the stable distribution (buster), these problems were mostly fixed
in version 4.19.37-5+deb10u2 or earlier.

We recommend that you upgrade your linux packages.

For the detailed security status of linux please refer to
its security tracker page at:

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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