CVE-2017-12188

arch/x86/kvm/mmu.c in the Linux kernel through 4.13.5, when nested virtualisation is used, does not properly traverse guest pagetable entries to resolve a guest virtual address, which allows L1 guest OS users to execute arbitrary code on the host OS or cause a denial of service (incorrect index during page walking, and host OS crash), aka an MMU potential stack buffer overrun.

Weakness

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Affected Software

Potential Mitigations

• Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
• D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
• Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
• Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
• For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

References

• http://www.securityfocus.com/bid/101267
• https://access.redhat.com/errata/RHSA-2018:0395
• https://access.redhat.com/errata/RHSA-2018:0412
• https://bugzilla.redhat.com/show_bug.cgi?id=1500380
• https://patchwork.kernel.org/patch/9996579/
• https://patchwork.kernel.org/patch/9996587/