Bug 1771486 (CVE-2019-18198) - CVE-2019-18198 kernel: reference count usage error in fib6_rule_suppress function in net/ipv6/fib6_rules.c
Summary: CVE-2019-18198 kernel: reference count usage error in fib6_rule_suppress func...
Keywords:
Status: NEW
Alias: CVE-2019-18198
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1771487 1814527
Blocks: 1771490
TreeView+ depends on / blocked
 
Reported: 2019-11-12 13:19 UTC by Guilherme de Almeida Suckevicz
Modified: 2020-04-03 04:31 UTC (History)
48 users (show)

Fixed In Version:
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Doc Text:
A flaw was found in the Linux kernel’s IPv6 routing system. A local attacker with the ability to configure routing can create a situation where they can corrupt memory or possibly escalate privileges.
Clone Of:
Environment:
Last Closed:


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Description Guilherme de Almeida Suckevicz 2019-11-12 13:19:45 UTC
A flaw was found in the Linux kernels IPV6 subsystem.  Route reference count usage error in the fib6_rule_suppress() function in the fib6 suppression feature of net/ipv6/fib6_rules.c.  A local attacker with the ability to trigger packets being sent over a specific route that implements suppress_prefixlength.  

The suppress_prefixlength routes are not standard and require administrative access to insert.


Upstream commit:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ca7a03c4175366a92cee0ccc4fec0038c3266e26

Comment 1 Guilherme de Almeida Suckevicz 2019-11-12 13:20:08 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1771487]

Comment 2 Justin M. Forbes 2019-11-12 18:06:44 UTC
This was fixed for Fedora with the 5.3.4 stable kernel updates.

Comment 7 Wade Mealing 2020-03-18 06:30:35 UTC
Mitigation:


As the IPV6 module will be auto-loaded when required, its use can be disabled  by preventing the module from loading with the following instructions:

https://access.redhat.com/solutions/8790

If the system requires IPV6 to work correctly, this mitigation may not be suitable.

If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.

Comment 10 Petr Matousek 2020-04-03 04:31:26 UTC
Statement:

This flaw is rated as moderate as setting up the condition requires CAP_NET_ADMIN privileges which are not available to regular users.


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