On 2/29/24 15:39, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
>
> As the comment in qapi/error, passing @errp to error_prepend() requires
> ERRP_GUARD():
>
> * = Why, when and how to use ERRP_GUARD() =
> *
> * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> ...
> * - It should not be passed to error_prepend(), error_vprepend() or
> * error_append_hint(), because that doesn't work with &error_fatal.
> * ERRP_GUARD() lifts these restrictions.
> *
> * To use ERRP_GUARD(), add it right at the beginning of the function.
> * @errp can then be used without worrying about the argument being
> * NULL or &error_fatal.
>
> ERRP_GUARD() could avoid the case when @errp is the pointer of
> error_fatal, the user can't see this additional information, because
> exit() happens in error_setg earlier than information is added [1].
>
> In hw/vfio/pci-quirks.c, there're 2 functions passing @errp to
> error_prepend() without ERRP_GUARD():
> - vfio_add_nv_gpudirect_cap()
> - vfio_add_vmd_shadow_cap()
>
> Their @errp parameters are so widely sourced that it is necessary to
> protect them with ERRP_GUARD().
>
> To avoid the issue like [1] said, add missing ERRP_GUARD() at the
> beginning of this function.
>
> [1]: Issue description in the commit message of commit ae7c80a7bd73
> ("error: New macro ERRP_GUARD()").
>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: "Cédric Le Goater" <clg@redhat.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Thanks,
C.
> ---
> hw/vfio/pci-quirks.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> index 84b1a7b9485c..496fd1ee86bd 100644
> --- a/hw/vfio/pci-quirks.c
> +++ b/hw/vfio/pci-quirks.c
> @@ -1538,6 +1538,7 @@ static bool is_valid_std_cap_offset(uint8_t pos)
>
> static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
> {
> + ERRP_GUARD();
> PCIDevice *pdev = &vdev->pdev;
> int ret, pos;
> bool c8_conflict = false, d4_conflict = false;
> @@ -1630,6 +1631,7 @@ static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
> #define VMD_SHADOW_CAP_LEN 24
> static int vfio_add_vmd_shadow_cap(VFIOPCIDevice *vdev, Error **errp)
> {
> + ERRP_GUARD();
> uint8_t membar_phys[16];
> int ret, pos = 0xE8;
>