Re: [PATCH] x86emul/fuzz: sanitize CR4 values

On 24/08/2026 8:41 am, Jan Beulich wrote:
> While the CPU policy is obtained from hardware, the CRn values to start
> with are taken from fuzzed input. Since most CR4 bits can only be set when
> the respective feature is indicated as available by CPUID, the emulator
> often only checks the CR4 bit. Without sanitization, assertions like the
> one in emul_test_read_xcr() (checking XSAVE support) could therefore
> trigger.
>
> Omit most paging-only bits from sanitization, as the core emulator doesn't
> itself walk page tables. LA57 wants checking for the bit being used by
> CANONICALIZE_MAYBE().
>
> Reported-by: Andrew Mbugua <[email protected]>
> Signed-off-by: Jan Beulich <[email protected]>

Acked-by: Andrew Cooper <[email protected]>