Re: [PATCH v2 2/3] MdeModulePkg/PciBusDxe: Fix possible uninitialized use

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: Sergei Dmitrouk <sergei@posteo.net>
> Sent: Wednesday, May 19, 2021 12:10 AM
> To: devel@edk2.groups.io
> Cc: Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>;
> Ni, Ray <ray.ni@intel.com>
> Subject: [PATCH v2 2/3] MdeModulePkg/PciBusDxe: Fix possible uninitialized
> use
> 
> If the function gets invalid value for the `ResizableBarOp` parameter and
> asserts are disabled, `Bit` can be used uninitialized.
> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Sergei Dmitrouk <sergei@posteo.net>
> ---
> 
> Notes:
>     v2:
>     - simplify if-statement to avoid unused branches
> 
>  MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
> b/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
> index 6bba28367165..4caac56f1dcd 100644
> --- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
> +++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
> @@ -1778,10 +1778,9 @@ PciProgramResizableBar (
> 
>      if (ResizableBarOp == PciResizableBarMax) {
>        Bit = HighBitSet64(Capabilities);
> -    } else if (ResizableBarOp == PciResizableBarMin) {
> +    } else {
> +      ASSERT (ResizableBarOp == PciResizableBarMin);
>        Bit = LowBitSet64(Capabilities);
> -    } else {
> -      ASSERT ((ResizableBarOp == PciResizableBarMax) || (ResizableBarOp ==
> PciResizableBarMin));


Reviewed-by: Hao A Wu <hao.a.wu@intel.com>

Best Regards,
Hao Wu


>      }
> 
>      ASSERT (Bit >= 0);
> --
> 2.17.6