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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