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24 November 2024, 11:20:20

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► Post reply ( Re: Possible bug in CreateMultiImageFromGLTexture of ImagingOpenGL.pas )

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[quote author=Johannes link=msg=1621 date=1517967724]
I have looked into the code of ImagingOpenGL.pas and found something weird:

[code]function CreateMultiImageFromGLTexture(const Texture: GLuint;
  var Images: TDynImageDataArray; MipLevels: LongInt; OverrideFormat: TImageFormat): Boolean;
var
  I, Width, Height, ExistingLevels: LongInt;
begin
  FreeImagesInArray(Images);
  SetLength(Images, 0);
  Result := False;
  if Byte(glIsTexture(Texture)) = GL_TRUE then
  begin
    // Check if desired mipmap level count is valid
    glBindTexture(GL_TEXTURE_2D, Texture);
    if MipLevels <= 0 then
      MipLevels := GetNumMipMapLevels(Width, Height);  //<- Here it tries to access uninitialized memory (Line 849)
    SetLength(Images, MipLevels);
[/code]

A possible fix would be:
[code]          
    if MipLevels <= 0 then
      begin
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, @Width);
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, @Height);
        MipLevels := GetNumMipMapLevels(Width, Height);
      end;
[/code]
[/quote]

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Topic summary

Posted by Galfar

- 23 August 2018, 14:17:52

Thanks for the report, just pushed your fix to the repo.

Posted by Johannes

- 7 February 2018, 02:42:04

I have looked into the code of ImagingOpenGL.pas and found something weird:

Code Select

function CreateMultiImageFromGLTexture(const Texture: GLuint;
  var Images: TDynImageDataArray; MipLevels: LongInt; OverrideFormat: TImageFormat): Boolean;
var
  I, Width, Height, ExistingLevels: LongInt;
begin
  FreeImagesInArray(Images);
  SetLength(Images, 0);
  Result := False;
  if Byte(glIsTexture(Texture)) = GL_TRUE then
  begin
    // Check if desired mipmap level count is valid
    glBindTexture(GL_TEXTURE_2D, Texture);
    if MipLevels <= 0 then
      MipLevels := GetNumMipMapLevels(Width, Height);  //<- Here it tries to access uninitialized memory (Line 849)
    SetLength(Images, MipLevels);

A possible fix would be:

Code Select

          
    if MipLevels <= 0 then
      begin
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, @Width);
        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, @Height);
        MipLevels := GetNumMipMapLevels(Width, Height);
      end;

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