[Webkit-unassigned] [Bug 50779] New: Large PNG images need a more robust size check

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=50779

           Summary: Large PNG images need a more robust size check
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Images
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: ctruta at chromium.org


Currently, PNG images of size 1000001x1 (1 megapixel, single-row or single-column) are rejected, while images of size 999999x999999 (ginormous, a little below 1 terapixel) are accepted by PNGImageDecoder. And yet, the difference in memory requirements between the two images is huge.
I propose the following limits:
image length: 2^20 - 1
image area: 2^29 - 1
The rationale for the image area limit is that RGBA images at 8 bits per channel should occupy no more than 2^31 bytes.

I wouldn't even mind if the image length restrictions were lifted, and all that's required were the 2^29 limit for the image area.

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