Re: [patch] MdeModulePkg/DisplayEngine: Remove useless NULL ptr check for NewPos

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 9 November 2018 at 01:19, Gao, Liming <liming.gao@intel.com> wrote:
> Ard:
>   This is a small fix. And, this patch is sent before the hard freeze. It is the low risk for this release. So, I push it.
>

OK, fair enough.

>>-----Original Message-----
>>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>>Sent: Friday, November 09, 2018 2:25 AM
>>To: Zeng, Star <star.zeng@intel.com>
>>Cc: Bi, Dandan <dandan.bi@intel.com>; edk2-devel@lists.01.org; Wu, Hao A
>><hao.a.wu@intel.com>; Dong, Eric <eric.dong@intel.com>; Gao, Liming
>><liming.gao@intel.com>
>>Subject: Re: [edk2] [patch] MdeModulePkg/DisplayEngine: Remove useless
>>NULL ptr check for NewPos
>>
>>On 8 November 2018 at 02:09, Zeng, Star <star.zeng@intel.com> wrote:
>>> Reviewed-by: Star Zeng <star.zeng@intel.com>
>>>
>>> -----Original Message-----
>>> From: Bi, Dandan
>>> Sent: Wednesday, November 7, 2018 10:53 PM
>>> To: edk2-devel@lists.01.org
>>> Cc: Gao, Liming <liming.gao@intel.com>; Dong, Eric <eric.dong@intel.com>;
>>Zeng, Star <star.zeng@intel.com>; Wu, Hao A <hao.a.wu@intel.com>
>>> Subject: [patch] MdeModulePkg/DisplayEngine: Remove useless NULL ptr
>>check for NewPos
>>>
>>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1306
>>>
>>> In function UiDisplayMenu, the NewPos ptr which used to point to the
>>highlight menu entry. It will always point to the menu entry which need to be
>>highlighted or the gMenuOption menu if the highlight menu is not found.
>>> So we can remove the NULL ptr check for NewPos in this function.
>>> And add the ASSERT code to avoid if any false positive reports of NULL
>>pointer dereference issue raised from static analysis.
>>>
>>> Cc: Liming Gao <liming.gao@intel.com>
>>> Cc: Eric Dong <eric.dong@intel.com>
>>> Cc: Star Zeng <star.zeng@intel.com>
>>> Cc: Hao Wu <hao.a.wu@intel.com>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Dandan Bi <dandan.bi@intel.com>
>>
>>Why was this patch merged today? Surely, this doesn't meet the hard
>>freeze requirements ?
>>
>>> ---
>>>  MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
>>b/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
>>> index 7390f954b6..44f087fe01 100644
>>> --- a/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
>>> +++ b/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
>>> @@ -2880,10 +2880,11 @@ UiDisplayMenu (
>>>        //             MenuOption is set to NULL in Repaint
>>>        // NewPos:     Current menu option that need to hilight
>>>        //
>>>        ControlFlag = CfUpdateHelpString;
>>>
>>> +      ASSERT (NewPos != NULL);
>>>        UpdateHighlightMenuInfo(NewPos, TopOfScreen, SkipValue);
>>>
>>>        if (SkipHighLight) {
>>>          SkipHighLight = FALSE;
>>>          MenuOption    = SavedMenuOption;
>>> @@ -2908,11 +2909,11 @@ UiDisplayMenu (
>>>          Temp2 = SkipValue;
>>>        } else {
>>>          Temp2 = 0;
>>>        }
>>>
>>> -      if (NewPos != NULL && (MenuOption == NULL || NewPos !=
>>&MenuOption->Link)) {
>>> +      if (MenuOption == NULL || NewPos != &MenuOption->Link) {
>>>          if (MenuOption != NULL) {
>>>            //
>>>            // Remove the old highlight menu.
>>>            //
>>>            Status = DisplayOneMenu (MenuOption,
>>> --
>>> 2.18.0.windows.1
>>>
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