A use-after-free issue was found in the way the Linux kernel's KVM hypervisor processed posted interrupts when nested(=1) virtualization is enabled. In nested_get_vmcs12_pages(), in case of an error while processing posted interrupt address, it unmaps the 'pi_desc_page' without resetting 'pi_desc' descriptor address, which is later used in pi_test_and_clear_on(). A guest user/process could use this flaw to crash the host kernel resulting in DoS or potentially gain privileged access to a system. Kernel versions before 4.14.91 and before 4.19.13 are vulnerable.
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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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://marc.info/?l=kvm&m=154514994222809&w=2 | third party advisory patch |
| https://usn.ubuntu.com/3872-1/ | third party advisory vendor advisory |
| https://usn.ubuntu.com/3878-1/ | third party advisory vendor advisory |
| https://usn.ubuntu.com/3871-5/ | third party advisory vendor advisory |
| https://usn.ubuntu.com/3878-2/ | third party advisory vendor advisory |
| https://usn.ubuntu.com/3871-4/ | third party advisory vendor advisory |
| http://www.securityfocus.com/bid/106254 | vdb entry third party advisory |
| https://lwn.net/Articles/775720/ | third party advisory |
| https://usn.ubuntu.com/3871-1/ | third party advisory vendor advisory |
| https://lwn.net/Articles/775721/ | third party advisory |
| https://usn.ubuntu.com/3871-3/ | third party advisory vendor advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16882 | issue tracking third party advisory patch |
| https://support.f5.com/csp/article/K80557033 | third party advisory |