Count overflow in FUSE request leading to use-after-free issues.
CVE: CVE-2019-11487
Component: kernel
CWE: CWE-416
Severity: Important
CVSS v3: 7.7/CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Release date: 2019-04-22T00:00:00+00:00

A flaw was found in the Linux kernel's implementation of the FUSE filesystem, where it allows a page reference counter overflow. If a page reference counter overflows into a negative value, it can be placed back into the "free" list for reuse by other applications. This flaw allows a local attacker who can manipulate memory page reference counters to cause memory corruption and possible privilege escalation by triggering a use-after-free condition.

The current attack requires the system to have approximately 140 GB of RAM for this attack to be performed. It may be possible that the attack can occur with fewer memory requirements.


Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
Preventing loading of the 'fuse' kernel module will prevent attackers from using this exploit against the system; howeve the functionality of being able to access the filesystems that would  be allowed by fuse would no longer be allowed . See “How do I blacklist a kernel module to prevent it from loading automatically?" ( https://access.redhat.com/solutions/41278) for instructions on how to disable the 'fuse' kernel module from autoloading. This mitigation may not be suitable if access to the functionality provided by fuse is required.