kernel/ucount.c in the Linux kernel 5.14 through 5.16.4, when unprivileged user namespaces are enabled, allows a use-after-free and privilege escalation because a ucounts object can outlive its namespace.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
| Link | Tags |
|---|---|
| https://github.com/torvalds/linux/commit/f9d87929d451d3e649699d0f1d74f71f77ad38f5 | third party advisory patch |
| https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f9d87929d451d3e649699d0f1d74f71f77ad38f5 | mailing list patch vendor advisory |
| https://www.openwall.com/lists/oss-security/2022/01/29/1 | mailing list exploit third party advisory |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HSR3AI2IQGRKZCHNKF6S25JGDKUEAWWL/ | mailing list vendor advisory |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VVSZKUJAZ2VN6LJ35J2B6YD6BOPQTU3B/ | mailing list vendor advisory |
| https://security.netapp.com/advisory/ntap-20220221-0001/ | third party advisory |