Re: [PATCH] hw/hyperv: Avoid crash if hyperv_find_cpu() passed invalid vp_index

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Jun 30, 2026 at 09:48:55AM +0100, Peter Maydell wrote:
> The hyperv_find_cpu() function finds a CPU from a CPU index; this is
> basically a wrapper around qemu_get_cpu().  It is allowed to fail, in
> which case it returns NULL, which its caller handles.  However, it
> includes an assertion check which accidentally assumes the CPU
> pointer is non-NULL.
> 
> We could assert only if cs != NULL, but the assertion here is not
> doing anything interesting -- hyperv_vp_index() is a trivial wrapper
> returning cs->cpu_index, so this is effectively asserting that
> qemu_get_cpu() did what it claims to do, i.e.  returned us the CPU
> matching the index we gave it.  qemu_get_cpu() is a simple "iterate
> through list and find matching CPU" which is unlikely to be buggy,
> and we don't feel the need to sanity-check it in any of our other
> many uses of it.  Drop the assertion entirely.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3568
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Checked only with make check / check-functional...
> ---
>  hw/hyperv/hyperv.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


With regards,
Daniel
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