RE: [PATCH 20/20] selftests/vfio: Fix VLA initialisation in vfio_pci_irq_set()

[Manish Honap]

> -----Original Message-----
> From: Dave Jiang <dave.jiang@xxxxxxxxx>
> Sent: 14 March 2026 03:54
> To: Manish Honap <mhonap@xxxxxxxxxx>; Aniket Agashe <aniketa@xxxxxxxxxx>;
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> Subject: Re: [PATCH 20/20] selftests/vfio: Fix VLA initialisation in
> vfio_pci_irq_set()
> 
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> 
> On 3/11/26 1:34 PM, mhonap@xxxxxxxxxx wrote:
> > From: Manish Honap <mhonap@xxxxxxxxxx>
> >
> > C does not permit initialiser expressions on variable-length arrays.
> > vfio_pci_irq_set() declared
> >
> > u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count] = {};
> >
> > where count is a function parameter, making buf a VLA.  GCC rejects
> > this with "variable-sized object may not be initialized".
> >
> > Replace the initialiser with an explicit memset() immediately after
> > the declaration.
> >
> > Fixes: 19faf6fd969c2 ("vfio: selftests: Add a helper library for VFIO
> > selftests")
> 
> Should this fix be split out from the series and sent ahead? Does not seem
> to be tied to the current implementation.

Yes, sent this for review to David Matlack and linux-kselftest

> 
> DJ
> 
> > Signed-off-by: Manish Honap <mhonap@xxxxxxxxxx>
> > ---
> >  tools/testing/selftests/vfio/lib/vfio_pci_device.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> > b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> > index fac4c0ecadef..3258e814f450 100644
> > --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> > +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> > @@ -26,8 +26,10 @@
> >  static void vfio_pci_irq_set(struct vfio_pci_device *device,
> >                            u32 index, u32 vector, u32 count, int *fds)
> > {
> > -     u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count] = {};
> > +     u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count];
> >       struct vfio_irq_set *irq = (void *)&buf;
> > +
> > +     memset(buf, 0, sizeof(buf));
> >       int *irq_fds = (void *)&irq->data;
> >
> >       irq->argsz = sizeof(buf);