CVE-2018-16882

A use-after-free issue was found in the way the Linux kernels 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.

Weakness

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• http://www.securityfocus.com/bid/106254
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16882
• https://lwn.net/Articles/775720/
• https://lwn.net/Articles/775721/
• https://marc.info/?l=kvm\u0026m=154514994222809\u0026w=2
• https://support.f5.com/csp/article/K80557033
• https://usn.ubuntu.com/3871-1/
• https://usn.ubuntu.com/3871-3/
• https://usn.ubuntu.com/3871-4/
• https://usn.ubuntu.com/3871-5/
• https://usn.ubuntu.com/3872-1/
• https://usn.ubuntu.com/3878-1/
• https://usn.ubuntu.com/3878-2/
• http://www.securityfocus.com/bid/106254
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16882
• https://lwn.net/Articles/775720/
• https://lwn.net/Articles/775721/
• https://marc.info/?l=kvm\u0026m=154514994222809\u0026w=2
• https://support.f5.com/csp/article/K80557033
• https://usn.ubuntu.com/3871-1/
• https://usn.ubuntu.com/3871-3/
• https://usn.ubuntu.com/3871-4/
• https://usn.ubuntu.com/3871-5/
• https://usn.ubuntu.com/3872-1/
• https://usn.ubuntu.com/3878-1/
• https://usn.ubuntu.com/3878-2/