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15 February 2021

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             AUSCERT External Security Bulletin Redistribution

                        linux-4.19 security update
                             15 February 2021


        AusCERT Security Bulletin Summary

Product:           linux-4.19
Publisher:         Debian
Operating System:  Debian GNU/Linux
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated      
                   Root Compromise                 -- Existing Account            
                   Modify Arbitrary Files          -- Remote with User Interaction
                   Denial of Service               -- Existing Account            
                   Access Confidential Data        -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-20177 CVE-2021-3347 CVE-2020-36158
                   CVE-2020-29661 CVE-2020-29660 CVE-2020-29569
                   CVE-2020-29568 CVE-2020-28374 CVE-2020-27830
                   CVE-2020-27825 CVE-2020-27815 

Reference:         ESB-2021.0553

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

- -------------------------------------------------------------------------
Debian LTS Advisory DLA-2557-1                debian-lts@lists.debian.org
https://www.debian.org/lts/security/                        Ben Hutchings
February 12, 2021                             https://wiki.debian.org/LTS
- -------------------------------------------------------------------------

Package        : linux-4.19
Version        : 4.19.171-2~deb9u1
CVE ID         : CVE-2020-27815 CVE-2020-27825 CVE-2020-27830 CVE-2020-28374
                 CVE-2020-29568 CVE-2020-29569 CVE-2020-29660 CVE-2020-29661
                 CVE-2020-36158 CVE-2021-3347 CVE-2021-20177
Debian Bug     : 970736 972345 977048 977615

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


    A flaw was reported in the JFS filesystem code allowing a local
    attacker with the ability to set extended attributes to cause a
    denial of service.


    Adam 'pi3' Zabrocki reported a use-after-free flaw in the ftrace
    ring buffer resizing logic due to a race condition, which could
    result in denial of service or information leak.


    Shisong Qin reported a NULL pointer dereference flaw in the Speakup
    screen reader core driver.


    David Disseldorp discovered that the LIO SCSI target implementation
    performed insufficient checking in certain XCOPY requests. An
    attacker with access to a LUN and knowledge of Unit Serial Number
    assignments can take advantage of this flaw to read and write to any
    LIO backstore, regardless of the SCSI transport settings.

CVE-2020-29568 (XSA-349)

    Michael Kurth and Pawel Wieczorkiewicz reported that frontends can
    trigger OOM in backends by updating a watched path.

CVE-2020-29569 (XSA-350)

    Olivier Benjamin and Pawel Wieczorkiewicz reported a use-after-free
    flaw which can be triggered by a block frontend in Linux blkback. A
    misbehaving guest can trigger a dom0 crash by continuously
    connecting / disconnecting a block frontend.


    Jann Horn reported a locking inconsistency issue in the tty
    subsystem which may allow a local attacker to mount a
    read-after-free attack against TIOCGSID.


    Jann Horn reported a locking issue in the tty subsystem which can
    result in a use-after-free. A local attacker can take advantage of
    this flaw for memory corruption or privilege escalation.


    A buffer overflow flaw was discovered in the mwifiex WiFi driver
    which could result in denial of service or the execution of
    arbitrary code via a long SSID value.


    It was discovered that PI futexes have a kernel stack use-after-free
    during fault handling. An unprivileged user could use this flaw to
    crash the kernel (resulting in denial of service) or for privilege


    A flaw was discovered in the Linux implementation of string matching
    within a packet. A privileged user (with root or CAP_NET_ADMIN) can
    take advantage of this flaw to cause a kernel panic when inserting
    iptables rules.

For Debian 9 stretch, these problems have been fixed in version

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:

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

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