Re: [edk2-devel] [PATCH v1 2/2] MdeModulePkg/Bus/Pci/UhciDxe: Fix FORWARD_NULL Coverity issues

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

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

Best Regards,
Hao Wu

> -----Original Message-----
> From: Ranbir Singh <rsingh@ventanamicro.com>
> Sent: Monday, July 17, 2023 7:39 PM
> To: devel@edk2.groups.io; rsingh@ventanamicro.com
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>; Veeresh
> Sangolli <veeresh.sangolli@dellteam.com>
> Subject: [PATCH v1 2/2] MdeModulePkg/Bus/Pci/UhciDxe: Fix
> FORWARD_NULL Coverity issues
> 
> From: Ranbir Singh <Ranbir.Singh3@Dell.com>
> 
> The function UsbHcGetPciAddressForHostMem has
> 
>   ASSERT ((Block != NULL)); and
> 
> and the function UsbHcFreeMem has
> 
>   ASSERT (Block != NULL);
> 
> statement after for loop, but these are applicable only in DEBUG mode.
> In RELEASE mode, if for whatever reasons there is no match inside for
> loop and the loop exits because of Block != NULL; condition, then there
> is no "Block" NULL pointer check afterwards and the code proceeds to do
> dereferencing "Block" which will lead to CRASH.
> 
> Hence, for safety add NULL pointer checks always.
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4211
> 
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Co-authored-by: Veeresh Sangolli <veeresh.sangolli@dellteam.com>
> Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
> Signed-off-by: Ranbir Singh <rsingh@ventanamicro.com>
> ---
>  MdeModulePkg/Bus/Pci/UhciDxe/UsbHcMem.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/MdeModulePkg/Bus/Pci/UhciDxe/UsbHcMem.c
> b/MdeModulePkg/Bus/Pci/UhciDxe/UsbHcMem.c
> index c3d46f60bed5..3794f888e132 100644
> --- a/MdeModulePkg/Bus/Pci/UhciDxe/UsbHcMem.c
> +++ b/MdeModulePkg/Bus/Pci/UhciDxe/UsbHcMem.c
> @@ -250,6 +250,11 @@ UsbHcGetPciAddressForHostMem (
>    }
> 
> 
> 
>    ASSERT ((Block != NULL));
> 
> +
> 
> +  if (Block == NULL) {
> 
> +    return 0;
> 
> +  }
> 
> +
> 
>    //
> 
>    // calculate the pci memory address for host memory address.
> 
>    //
> 
> @@ -536,6 +541,10 @@ UsbHcFreeMem (
>    //
> 
>    ASSERT (Block != NULL);
> 
> 
> 
> +  if (Block == NULL) {
> 
> +    return;
> 
> +  }
> 
> +
> 
>    //
> 
>    // Release the current memory block if it is empty and not the head
> 
>    //
> 
> --
> 2.34.1



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