Re: [PATCH] Fix edit on screens with more than 200 columns

["Witt, Sebastian" <sebastian.witt@siemens.com>]

Like this?

If the shell edit command is used on a screen with more than
200 columns, we get a buffer overflow. This always allocates a pool for the columns.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Sebastian Witt <sebastian.witt@siemens.com>

---
 .../UefiShellDebug1CommandsLib.c                          | 15 ++++++++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
index 6ebf002..d81dd01 100644
--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
@@ -302,12 +302,21 @@ EditorClearLine (
   IN UINTN LastRow
   )
 {
-  CHAR16 Line[200];
+  CHAR16 *Line;
 
   if (Row == 0) {
     Row = 1;
   }
 
+  // Allocate buffer for columns
+  Line = AllocateZeroPool (LastCol*(sizeof(CHAR16) + 1));
+  if (Line == NULL) {
+    return;
+  }
+  
   //
   // prepare a blank line
   //
@@ -326,6 +335,10 @@ EditorClearLine (
   // print out the blank line
   //
   ShellPrintEx (0, ((INT32)Row) - 1, Line);
+  
+  FreePool (Line);
 }
 
 /**
-- 
2.1.4


-----Original Message-----
From: Carsey, Jaben [mailto:jaben.carsey@intel.com] 
Sent: Dienstag, 24. Januar 2017 18:36
To: Witt, Sebastian (DF FA AS DH KHE 1); edk2-devel@lists.01.org
Cc: Carsey, Jaben
Subject: RE: [PATCH] Fix edit on screens with more than 200 columns

I didn't mean a 400 static, I meant start by allocating 400 and simplify the end of the function...

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of 
> Witt, Sebastian
> Sent: Tuesday, January 24, 2017 8:48 AM
> To: Carsey, Jaben <jaben.carsey@intel.com>; edk2-devel@lists.01.org
> Subject: Re: [edk2] [PATCH] Fix edit on screens with more than 200 
> columns
> Importance: High
> 
> Only performance. But I haven't measured if there is a big difference 
> between static buffer and AllocateZeroPool. I wouldn't use a fixed value.
> There may be a display device with more than 400 columns. Otherwise 
> one can always allocate the [LastCol + 1] buffer.
> 
> -----Original Message-----
> From: Carsey, Jaben [mailto:jaben.carsey@intel.com]
> Sent: Dienstag, 24. Januar 2017 17:27
> To: Witt, Sebastian (DF FA AS DH KHE 1); edk2-devel@lists.01.org
> Cc: Carsey, Jaben
> Subject: RE: [PATCH] Fix edit on screens with more than 200 columns
> 
> Is there a reason to not just always start with allocating the 400 and 
> then we don't need to complicate the end to conditionally free the buffer?
> 
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf 
> > Of Witt, Sebastian
> > Sent: Tuesday, January 24, 2017 5:14 AM
> > To: edk2-devel@lists.01.org
> > Subject: [edk2] [PATCH] Fix edit on screens with more than 200 
> > columns
> > Importance: High
> >
> > If the shell edit command is used on a screen with more than
> > 200 columns, we get a buffer overflow. This increases the default 
> > buffer size to
> > 400 columns and allocates a pool when this is not enough.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Sebastian Witt <sebastian.witt@siemens.com>
> >
> > ---
> >  .../UefiShellDebug1CommandsLib.c                          | 15 ++++++++++++++-
> >  1 file changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git
> >
> a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsL
> > i
> > b.c
> >
> b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsL
> > i
> > b.c
> > index 6ebf002..d81dd01 100644
> > ---
> >
> a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsL
> > i
> > b.c
> > +++
> >
> b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> d
> > +++ sLib.c
> > @@ -302,12 +302,21 @@ EditorClearLine (
> >    IN UINTN LastRow
> >    )
> >  {
> > -  CHAR16 Line[200];
> > +  CHAR16 Buffer[400];
> > +  CHAR16 *Line = Buffer;
> >
> >    if (Row == 0) {
> >      Row = 1;
> >    }
> >
> > +  // If there are more columns than our buffer can contain, 
> > + allocate new buffer  if (LastCol >= (sizeof (Buffer) / sizeof (CHAR16))) {
> > +    Line = AllocateZeroPool (LastCol*(sizeof(CHAR16) + 1));
> > +    if (Line == NULL) {
> > +      return;
> > +    }
> > +  }
> > +
> >    //
> >    // prepare a blank line
> >    //
> > @@ -326,6 +335,10 @@ EditorClearLine (
> >    // print out the blank line
> >    //
> >    ShellPrintEx (0, ((INT32)Row) - 1, Line);
> > +
> > +  // Free if allocated
> > +  if (Line != Buffer)
> > +    FreePool (Line);
> >  }
> >
> >  /**
> > --
> > 2.1.4
> >
> > With best regards,
> > Sebastian Witt
> >
> > Siemens AG
> > Digital Factory Division
> > Factory Automation
> > Automation Products and Systems
> > DF FA AS DH KHE 1
> > Oestliche Rheinbrueckenstr. 50
> > 76187 Karlsruhe, Germany
> > Tel.: +49 721 595-5326
> > mailto:sebastian.witt@siemens.com
> >
> > www.siemens.com/ingenuityforlife
> >
> > Siemens Aktiengesellschaft: Chairman of the Supervisory Board: 
> > Gerhard Cromme; Managing Board: Joe Kaeser, Chairman, President and 
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