[Webkit-unassigned] [Bug 241839] New: GIFImageDecoder: Can't render some corrupted GIF images of the 88x31 GIF Collection

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=241839

            Bug ID: 241839
           Summary: GIFImageDecoder: Can't render some corrupted GIF
                    images of the 88x31 GIF Collection
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Images
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: Hironori.Fujii at sony.com
                CC: sabouhallawa at apple.com

GIFImageDecoder: Can't render some corrupted GIF images of the 88x31 GIF Collection

Non-cocoa ports are uing GIFImageDecoder.
It can't render some images of https://cyber.dabamos.de/88x31/ , but Safari, Chrome and Firefox can.

For example,

https://cyber.dabamos.de/88x31/besteyes2.gif
https://cyber.dabamos.de/88x31/epicenter.gif
https://cyber.dabamos.de/88x31/filetransit.gif


GIFImageReader.cpp determines they are corrupted in the following condition.
`*currentComponent` was 0.

https://github.com/WebKit/WebKit/blob/49c1b53f803fe6952e293bfde206b22dc4ceadef/Source/WebCore/platform/image-decoders/gif/GIFImageReader.cpp#L502-L508

>             // If we get anything other than ',' (image separator), '!'
>             // (extension), or ';' (trailer), there is extraneous data
>             // between blocks. The GIF87a spec tells us to keep reading
>             // until we find an image separator, but GIF89a says such
>             // a file is corrupt. We follow GIF89a and bail out.
>             if (*currentComponent != ',')
>                 return false;

10635 at main added the code.

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