Bug 1832543 (CVE-2020-12655) - CVE-2020-12655 kernel: sync of excessive duration via an XFS v5 image with crafted metadata
Summary: CVE-2020-12655 kernel: sync of excessive duration via an XFS v5 image with cr...
Keywords:
Status: NEW
Alias: CVE-2020-12655
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1837191 1837192 1837193 1837194 1837195 1832545
Blocks: 1832546
TreeView+ depends on / blocked
 
Reported: 2020-05-06 19:41 UTC by Guilherme de Almeida Suckevicz
Modified: 2020-06-01 09:46 UTC (History)
49 users (show)

Fixed In Version:
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A flaw was discovered in the XFS source in the Linux kernel. This flaw allows an attacker with the ability to mount an XFS filesystem, to trigger a denial of service while attempting to sync a file located on an XFS v5 image with crafted metadata.
Clone Of:
Environment:
Last Closed:


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Description Guilherme de Almeida Suckevicz 2020-05-06 19:41:04 UTC
An issue was discovered in xfs_agf_verify in fs/xfs/libxfs/xfs_alloc.c in the Linux kernel. An attacker who is able to mount a xfs filesystem can trigger a denial of service while attempting to sync a file located an XFS v5 image with crafted metadata.

Reference and upstream commit:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d0c7feaf87678371c2c09b3709400be416b2dc62
https://lore.kernel.org/linux-xfs/20200221153803.GP9506@magnolia/

Comment 1 Guilherme de Almeida Suckevicz 2020-05-06 19:43:08 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1832545]

Comment 4 Wade Mealing 2020-05-19 03:45:41 UTC
Mitigation:


This flaw requires an attacker being able to have the system mount a crafted filesystem.

If the xfs filesystem is not in use, the 'xfs' kernel module can be blacklisted and the module
will not be loaded when the filesystem is mounted, mounting will fail.

However, if this filesystem is in use, this workaround will not be suitable.

To find out how to blacklist the "xfs" kernel module please see https://access.redhat.com/solutions/41278 or contact Red hat Global Support services

Comment 8 Petr Matousek 2020-05-26 12:20:47 UTC
Statement:

This issue is rated as having Low impact because of the preconditions needed to trigger it (administrative account or physical access).


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