[OpenJDK 2D-Dev] [10] RFR JDK-8190332: PngReader throws NegativeArraySizeException/OOM error when IHDR width is very large

[Jayathirth D V]

Hello All,

 

Please review the following fix in JDK10 :

 

Bug : https://bugs.openjdk.java.net/browse/JDK-8190332 

Webrev : http://cr.openjdk.java.net/~jdv/8190332/webrev.00/ 

 

Issue : 

Two types of issues are fixed under the same solution, so HYPERLINK "https://bugs.openjdk.java.net/browse/JDK-8190511"JDK-8190511 is closed as duplicate of this issue.

1) PNGImageReader throws OOM error when IHDR width equals/or greater than VM's array size limit.

2) PNGImageReader throws NegativeArraySizeException when IHDR width value is very high.

 

Root cause : 

1)      VM doesn't allow creation of array with Size >= ((2 to the power of 31) - 2) so we throw OOM error.

2)      We use width from IHDR to calculate needed "bytesPerRow" value as "(inputBands*passWidth*bitDepth + 7)/8". When IHDR width is very high we overflow the integer size of bytesPerRow and when we try to create array using bytesPerRow it throws NegativeArraySizeException.

 

Solution :

According to PNG spec maximum value that can be stored in IHDR width/height is (2 to the power of 31). We can't support PNG images with so large height/width, because based on other parameters like inputsBands, bitDepth we will definitely           overflow than the maximum buffer value of VM. Also PNG is not a preferred format for such kind of large images.

                Instead of catching these OOMError/NegativeArraySizeException at many different levels in PNGImageReader we can catch Throwable at higher level and convert OOMError/ NegativeArraySizeException into IIOException.

 

Thanks,

Jay

 
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