Re: Endless loop in version 1.6.26

On Fri, Dec 30, 2016 at 10:37 AM, Glenn Randers-Pehrson <[email protected]>
wrote:

> The trouble is that zlib returns ZLIB_DATA_ERROR for various reasons, one
> of which
> is a missing or incorrect ADLER32.
>
>
>>
>> I'd recommend leaving it as it is with just the Mozilla fix to do
>> png_benign_error/png_error
>>
>
> The problem with that is other ZLIB_DATA_ERROR that should be abandoned.
> One
> of those caused the "endless loop" mentioned in the title of this thread.
>

Yes, but if the app has to switch it on the endless loop can't happen in
any existing app.  As it is the endless loop is far worse than an image
that doesn't display.

In other words, since it has to happen because of pressure from Mozilla
then it should only happen in Mozilla until they've tested it really well;
we don't have the resources to test this (as demonstrated by the endless
loop) and we've got into trouble in the past by apparently benign changes
to the logic of the inflate code.

There are so many different cases to test, we don't have test cases in
'make check' for error handling and even adding things like 1-byte IDAT
chunks to the test code has the effect of slowing down the checks.

-- 
John Bowler <[email protected]>
+1 (541) 450-9885
PO BOX 3151
KERBY OR 97531-3151
USA

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