Bug 1548412 (CVE-2017-13166) - CVE-2017-13166 kernel: v4l2: disabled memory access protection mechanism allowing privilege escalation
Summary: CVE-2017-13166 kernel: v4l2: disabled memory access protection mechanism allo...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2017-13166
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1548413 1548429 1548430 1548431 1548432 1548726 1548727 1548728 1550058 1550059 1550060
Blocks: 1548415
TreeView+ depends on / blocked
 
Reported: 2018-02-23 12:43 UTC by Vladis Dronov
Modified: 2021-02-17 00:46 UTC (History)
20 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A bug in the 32-bit compatibility layer of the ioctl handling code of the v4l2 video driver in the Linux kernel has been found. A memory protection mechanism ensuring that user-provided buffers always point to a userspace memory were disabled, allowing destination address to be in a kernel space. This flaw could be exploited by an attacker to overwrite a kernel memory from an unprivileged userspace process, leading to privilege escalation.
Clone Of:
Environment:
Last Closed: 2019-06-08 03:41:04 UTC
Embargoed:

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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2018:0676 0 None None None 2018-04-10 08:19:53 UTC
Red Hat Product Errata RHSA-2018:1062 0 None None None 2018-04-10 09:43:59 UTC
Red Hat Product Errata RHSA-2018:1130 0 None None None 2018-04-17 16:24:06 UTC
Red Hat Product Errata RHSA-2018:1170 0 None None None 2018-04-17 15:33:31 UTC
Red Hat Product Errata RHSA-2018:1319 0 None None None 2018-05-08 18:59:50 UTC
Red Hat Product Errata RHSA-2018:2948 0 None None None 2018-10-30 08:58:11 UTC

Description Vladis Dronov 2018-02-23 12:43:00 UTC 
A bug in the 32-bit compatibility layer of the ioctl handling code of the v4l2 video driver in the Linux kernel has been found. A memory protection mechanism ensuring that user-provided buffers always point to a userspace memory were disabled, allowing destination address to be in a kernel space. This flaw could be exploited by an attacker to overwrite a kernel memory from an unprivileged userspace process, leading to privilege escalation.

References:

https://source.android.com/security/bulletin/pixel/2017-12-01#kernel-components

https://nvd.nist.gov/vuln/detail/CVE-2017-13166

An upstream fix:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a1dfb4c48cc1e64eeb7800a27c66a6f7e88d075a
Comment 1 Vladis Dronov 2018-02-23 12:43:43 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1548413]
Comment 2 Vladis Dronov 2018-02-23 12:53:23 UTC 
details of the flaw impact per upstream commit a1dfb4c48cc1:

...As a workaround, set_fs(KERNEL_DS) is called to temporarily disable this extra safety check and allow kernel pointers. However, this might introduce a security vulnerability: The result of the 32-bit to 64-bit conversion is writeable by user space because the output buffer has been allocated via compat_alloc_user_space(). A malicious user space process could then manipulate pointers inside this output buffer, and due to the previous set_fs(KERNEL_DS) call, functions like get_user() or put_user() no longer prevent kernel memory access.
Comment 6 Justin M. Forbes 2018-02-23 15:17:37 UTC 
This was fixed for Fedora with the 4.15.4 stable updates.
Comment 9 Vladis Dronov 2018-02-28 12:18:04 UTC 
Mitigation:

A systemtap script intercepting v4l2_compat_ioctl32() function of the [videodev] module and making it to return -ENOIOCTLCMD error value would work just fine, except breaking all 32bit video capturing software, but not 64bit ones.

Alternatively, blacklisting [videodev] module will work too, but it will break all video capturing software.
Comment 12 errata-xmlrpc 2018-04-10 08:19:44 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:0676 https://access.redhat.com/errata/RHSA-2018:0676
Comment 13 errata-xmlrpc 2018-04-10 09:43:49 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:1062 https://access.redhat.com/errata/RHSA-2018:1062
Comment 14 errata-xmlrpc 2018-04-17 15:33:19 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise MRG 2

Via RHSA-2018:1170 https://access.redhat.com/errata/RHSA-2018:1170
Comment 15 errata-xmlrpc 2018-04-17 16:23:55 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.4 Extended Update Support

Via RHSA-2018:1130 https://access.redhat.com/errata/RHSA-2018:1130
Comment 16 errata-xmlrpc 2018-05-08 18:59:41 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2018:1319 https://access.redhat.com/errata/RHSA-2018:1319
Comment 17 errata-xmlrpc 2018-10-30 08:58:01 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:2948 https://access.redhat.com/errata/RHSA-2018:2948
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