On 2026-06-15 08:47 AM, Alex Mastro wrote:
Please follow the local convention for shortlogs:
vfio: selftests: Description of the commit
> Allocate VFIO ioctl requests dynamically instead of using VLAs. GCC 11.5.0
> rejects initialized VLAs with:
>
> error: variable-sized object may not be initialized
>
> The replaced stack u8 arrays also do not guarantee native struct alignment
> for the aliased pointers.
>
> Fixes: 19faf6fd969c ("vfio: selftests: Add a helper library for VFIO
> selftests")
> Fixes: 20face8c75ff ("vfio: selftests: Add helper to set/override a vf_token")
> Assisted-by: Codex:gpt-5.5-high
> Tested-by: Vipin Sharma <[email protected]>
> Reviewed-by: Vipin Sharma <[email protected]>
> Signed-off-by: Alex Mastro <[email protected]>
> ---
> Changes in v2:
> - Reverse xmas tree variable ordering
> - Link to v1:
> https://patch.msgid.link/20260612-scratch-amastro-vfio-selftests-avoid-vlas-v1-1-ba3acb635...@fb.com
>
> To: David Matlack <[email protected]>
> To: Alex Williamson <[email protected]>
> To: Shuah Khan <[email protected]>
> To: Raghavendra Rao Ananta <[email protected]>
> To: Vipin Sharma <[email protected]>
> Cc: Shuah Khan <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> tools/testing/selftests/vfio/lib/vfio_pci_device.c | 28
> +++++++++++++---------
> 1 file changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> index 94dc5fcecbeb..c65d5ed33e51 100644
> --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> @@ -30,13 +30,12 @@
> 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];
> - struct vfio_irq_set *irq = (void *)&buf;
> - int *irq_fds = (void *)&irq->data;
> + size_t irq_size = sizeof(struct vfio_irq_set) + sizeof(int) * count;
optional nit: s/irq_size/argsz/ (same for vfio_device_feature_ioctl())
> + struct vfio_irq_set *irq;
>
> - memset(buf, 0, sizeof(buf));
> -
> - irq->argsz = sizeof(buf);
> + irq = calloc(1, irq_size);
> + VFIO_ASSERT_NOT_NULL(irq);
Could you add a precursor patch to add a calloc_assert() helper to
assert.h next to ioctl_assert() and snprintf_assert()? It looks like
there's quite a bit of code that repeats the
calloc()/VFIO_ASSERT_NOT_NULL() pattern.
> + irq->argsz = irq_size;
> irq->flags = VFIO_IRQ_SET_ACTION_TRIGGER;
> irq->index = index;
> irq->start = vector;
> @@ -44,12 +43,13 @@ static void vfio_pci_irq_set(struct vfio_pci_device
> *device,
>
> if (count) {
> irq->flags |= VFIO_IRQ_SET_DATA_EVENTFD;
> - memcpy(irq_fds, fds, sizeof(int) * count);
> + memcpy(irq->data, fds, sizeof(int) * count);
> } else {
> irq->flags |= VFIO_IRQ_SET_DATA_NONE;
> }
>
> ioctl_assert(device->fd, VFIO_DEVICE_SET_IRQS, irq);
> + free(irq);
> }
>
> void vfio_pci_irq_trigger(struct vfio_pci_device *device, u32 index, u32
> vector)
> @@ -118,15 +118,21 @@ static void vfio_pci_irq_get(struct vfio_pci_device
> *device, u32 index,
> static int vfio_device_feature_ioctl(int fd, u32 flags, void *data,
> size_t data_size)
> {
> - u8 buffer[sizeof(struct vfio_device_feature) + data_size] = {};
> - struct vfio_device_feature *feature = (void *)buffer;
> + size_t feature_size = sizeof(struct vfio_device_feature) + data_size;
> + struct vfio_device_feature *feature;
> + int ret;
>
> + feature = calloc(1, feature_size);
> + VFIO_ASSERT_NOT_NULL(feature);
> memcpy(feature->data, data, data_size);
>
> - feature->argsz = sizeof(buffer);
> + feature->argsz = feature_size;
> feature->flags = flags;
>
> - return ioctl(fd, VFIO_DEVICE_FEATURE, feature);
> + ret = ioctl(fd, VFIO_DEVICE_FEATURE, feature);
> + free(feature);
> +
> + return ret;
> }
>
> static void vfio_device_feature_set(int fd, u16 feature, void *data, size_t
> data_size)
>
> ---
> base-commit: a26b499b757cfc8bbff1088bb1b844639e250893
> change-id: 20260612-scratch-amastro-vfio-selftests-avoid-vlas-395eb3dcb3ab
>
> Best regards,
> --
> Alex Mastro <[email protected]>
>
