CVE-2019-18683

Published: 4 November 2019

An issue was discovered in drivers/media/platform/vivid in the Linux kernel through 5.3.8. It is exploitable for privilege escalation on some Linux distributions where local users have /dev/video0 access, but only if the driver happens to be loaded. There are multiple race conditions during streaming stopping in this driver (part of the V4L2 subsystem). These issues are caused by wrong mutex locking in vivid_stop_generating_vid_cap(), vivid_stop_generating_vid_out(), sdr_cap_stop_streaming(), and the corresponding kthreads. At least one of these race conditions leads to a use-after-free.

From the Ubuntu Security Team

It was discovered that a race condition existed in the Virtual Video Test Driver in the Linux kernel. An attacker with write access to /dev/video0 on a system with the vivid module loaded could possibly use this to gain administrative privileges.

Notes

This rarely used driver module cannot be loaded by an unprivileged
user so the impact is lessened

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18683
• https://www.openwall.com/lists/oss-security/2019/11/02/1
• https://lore.kernel.org/lkml/20191103221719.27118-1-alex.popov@linux.com/
• https://ubuntu.com/security/notices/USN-4254-1
• https://ubuntu.com/security/notices/USN-4254-2
• https://ubuntu.com/security/notices/USN-4258-1
• https://ubuntu.com/security/notices/USN-4284-1
• https://ubuntu.com/security/notices/USN-4287-1
• https://ubuntu.com/security/notices/USN-4287-2
• NVD
• Launchpad
• Debian