CVE-2021-47461

Name	CVE-2021-47461
Description	In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	buster	4.19.249-2	fixed
	buster (security)	4.19.304-1	fixed
	bullseye	5.10.209-2	fixed
	bullseye (security)	5.10.218-1	fixed
	bookworm	6.1.76-1	fixed
	bookworm (security)	6.1.90-1	fixed
	sid, trixie	6.8.12-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version
linux	source	buster	(not affected)
linux	source	bullseye	5.10.84-1
linux	source	(unstable)	5.14.16-1

[buster] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca (5.15-rc7)