An issue was discovered in drivers/media/platform/vivid in the Linux kernel. 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. Reference: https://seclists.org/oss-sec/2019/q4/43 https://www.openwall.com/lists/oss-security/2019/11/02/1 https://lore.kernel.org/lkml/20191103221719.27118-1-alex.popov@linux.com/
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1771828]
The vivid drivers are not enabled for Fedora as they depend on CONFIG_V4L_TEST_DRIVERS.
External References: https://seclists.org/oss-sec/2019/q4/43 https://www.openwall.com/lists/oss-security/2019/11/02/1 https://lore.kernel.org/lkml/20191103221719.27118-1-alex.popov@linux.com/