[PATCH v2] MdeModulePkg/DxeCore: Add comments for the ASSERT to check NULL ptr

[PATCH v2] MdeModulePkg/DxeCore: Add comments for the ASSERT to check NULL ptr

[Hao Wu]

Commit 8932679df5be046feba30fae80776c5815232a08 adds an ASSERT for
checking NULL pointer dereference.

The ASSERT added here is for addressing a false positive NULL pointer
dereference issue raised from static analysis.

This commit adds comments to clarify the reason for using ASSERT as the
check.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
---
 MdeModulePkg/Core/Dxe/Hand/Handle.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Core/Dxe/Hand/Handle.c b/MdeModulePkg/Core/Dxe/Hand/Handle.c
index 2db441725c..86a4065733 100644
--- a/MdeModulePkg/Core/Dxe/Hand/Handle.c
+++ b/MdeModulePkg/Core/Dxe/Hand/Handle.c
@@ -1175,10 +1175,18 @@ Done:
     //
     if (!EFI_ERROR (Status) || Status == EFI_ALREADY_STARTED) {
       //
+      // According to above logic, if 'Prot' is NULL, then the 'Status' must be
+      // EFI_UNSUPPORTED. Here the 'Status' is not EFI_UNSUPPORTED, so 'Prot'
+      // must be not NULL.
+      //
+      // The ASSERT here is for addressing a false positive NULL pointer
+      // dereference issue raised from static analysis.
+      //
+      ASSERT (Prot != NULL);
+      //
       // EFI_ALREADY_STARTED is not an error for bus driver.
       // Return the corresponding protocol interface.
       //
-      ASSERT (Prot != NULL);
       *Interface = Prot->Interface;
     } else if (Status == EFI_UNSUPPORTED) {
       //
-- 
2.12.0.windows.1

Re: [PATCH v2] MdeModulePkg/DxeCore: Add comments for the ASSERT to check NULL ptr

[Yao, Jiewen]

Reviewed-by: Jiewen.yao@intel.com

> -----Original Message-----
> From: Wu, Hao A
> Sent: Friday, September 29, 2017 9:28 AM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Zeng, Star <star.zeng@intel.com>; Kinney,
> Michael D <michael.d.kinney@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> Subject: [PATCH v2] MdeModulePkg/DxeCore: Add comments for the ASSERT to
> check NULL ptr
> 
> Commit 8932679df5be046feba30fae80776c5815232a08 adds an ASSERT for
> checking NULL pointer dereference.
> 
> The ASSERT added here is for addressing a false positive NULL pointer
> dereference issue raised from static analysis.
> 
> This commit adds comments to clarify the reason for using ASSERT as the
> check.
> 
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  MdeModulePkg/Core/Dxe/Hand/Handle.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Core/Dxe/Hand/Handle.c
> b/MdeModulePkg/Core/Dxe/Hand/Handle.c
> index 2db441725c..86a4065733 100644
> --- a/MdeModulePkg/Core/Dxe/Hand/Handle.c
> +++ b/MdeModulePkg/Core/Dxe/Hand/Handle.c
> @@ -1175,10 +1175,18 @@ Done:
>      //
>      if (!EFI_ERROR (Status) || Status == EFI_ALREADY_STARTED) {
>        //
> +      // According to above logic, if 'Prot' is NULL, then the 'Status' must be
> +      // EFI_UNSUPPORTED. Here the 'Status' is not EFI_UNSUPPORTED, so
> 'Prot'
> +      // must be not NULL.
> +      //
> +      // The ASSERT here is for addressing a false positive NULL pointer
> +      // dereference issue raised from static analysis.
> +      //
> +      ASSERT (Prot != NULL);
> +      //
>        // EFI_ALREADY_STARTED is not an error for bus driver.
>        // Return the corresponding protocol interface.
>        //
> -      ASSERT (Prot != NULL);
>        *Interface = Prot->Interface;
>      } else if (Status == EFI_UNSUPPORTED) {
>        //
> --
> 2.12.0.windows.1