Bug 1784923 (CVE-2019-19816) - CVE-2019-19816 kernel: out-of-bounds write in __btrfs_map_block in fs/btrfs/volumes.c
Summary: CVE-2019-19816 kernel: out-of-bounds write in __btrfs_map_block in fs/btrfs/v...
Keywords:
Status: CLOSED WONTFIX
Alias: CVE-2019-19816
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: 1784925 1819509 1819510 1819511 1819512 1819513
Blocks: 1784924
TreeView+ depends on / blocked
 
Reported: 2019-12-18 17:58 UTC by Guilherme de Almeida Suckevicz
Modified: 2023-09-26 14:05 UTC (History)
48 users (show)

Fixed In Version:
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Doc Text:
A flaw was found in the implementation of the BTRFS file system code in the Linux kernel. An attacker, who is able to mount a crafted BTRFS filesystem and perform common filesystem operations, can possibly cause an out-of-bounds write to memory. This could lead to memory corruption or privilege escalation.
Clone Of:
Environment:
Last Closed: 2020-04-01 09:04:21 UTC
Embargoed:

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Description Guilherme de Almeida Suckevicz 2019-12-18 17:58:57 UTC 
A flaw was found in the implementation of the BTRFS file system code.  An attacker who is able to mount (or convince someone to mount) a crafted BTRFS filesystem and performing common filesystem operations can possibly cause an out-of-bounds write to memory.

This could lead to memory corruption or possibly privilege escalation.  

Reference:
https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19816
Comment 1 Guilherme de Almeida Suckevicz 2019-12-18 17:59:55 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1784925]
Comment 8 Eric Christensen 2020-04-01 15:53:10 UTC 
Mitigation:

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

# echo "install btrfs /bin/true" >> /etc/modprobe.d/disable-btrfs.conf

The system will need to be restarted if the BTRFS modules are loaded, it may be possible to unload them. In most circumstances, the BTRFS kernel modules will be unable to be unloaded while any BTRFS filesystems are mounted or in use.

If the system requires this module 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 9 Petr Matousek 2020-04-03 04:42:44 UTC 
Statement:

This flaw is rated as having Moderate impact, the attacker would require physical access to the system and also a local account to abuse the use-after-free.
Comment 10 Justin M. Forbes 2020-06-26 17:14:47 UTC 
This was fixed for Fedora with the 5.2 kernel rebases.
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