KASAN example

[SuibianP]

According to https://www.microsoft.com/en-us/security/blog/2023/01/26/introducing-kernel-sanitizers-on-microsoft-platforms/, Kernel AddressSanitizer (KASAN) is available on Windows for kernel-mode. However, there is very limited documentation as to how to use it. It would be nice to have an example detailing the way to build a driver with KASAN support.

[v-junyli]

Hi,

KASAN is not yet in the current release, it will be in the release next month (2410D), which should be out early November.

[JohnMcSandwich]

@SuibianP - The documentation for KASAN was published today: https://learn.microsoft.com/en-us/windows-hardware/drivers/devtest/kasan.

I have a pending PR to add a KASAN demo to the samples: https://github.com/microsoft/Windows-driver-samples/pull/1228.

[PeterGV]

In addition to the sample, it would be extremely helpful if the documentation described, specifically, how KASAN differs from/adds to the already existing Driver Verifier (which does very efficient pool overrun checking as well as use-after-free checks) and stack overrun checking. Why would a KM dev want to use KASAN if I already have Verifier enabled? Can they co-exist? Do they interact? What are the costs/benefits/tradeoffs.

[JakobL-MSFT]

Huge shoutout to @JohnMcSandwich for making the KASAN scenario work for 3rd party device drivers and even providing a sample.

To provide a high-level answer to Peter's question:

• DV and KASAN are complimentary.
• DV is "lightweight" (as you do not need to special compile) whereas KASAN requires a special compilation
• DV can only "see" what goes on "on the edge" of the driver whereas KASAN can intercept "inside" of a driver. (Exception to this: DV does have special treatment of memory manager / IRQL style checks where we bug check based on page violations rather than based on the specific bug in the driver itself (so bugcheck based on a symptom rather than necessarily at the immediate point of failure).
• DV has tons of driver specific rules. KASAN is focused on generic memory checks.

I know what you really want is a more comprehensive and data driven answer. I don't have that.

I bet there are many other angles, but that's my 2 cents...

Jakob

References:

• https://www.microsoft.com/en-us/security/blog/2023/01/26/introducing-kernel-sanitizers-on-microsoft-platforms/
• https://learn.microsoft.com/en-us/windows-hardware/drivers/devtest/kasan
• https://github.com/microsoft/Windows-driver-samples/blob/main/tools/kasan/samples/KasanDemo-WDM/README.md