CVE-2017-13775: GraphicsMagick 1.3.26 Denial of Service issue in ReadJNXImage() in coders/jnx.c

["孙浩" <tony.sh () alibaba-inc com>]

Hi all.
Description:graphicsmagick is a collection of tools and libraries for many image formats.
We found a denial of service (DoS) issue in jnx.c at line 326, GraphicsMagick-1.3.26.The vulnerable code snippet is 
shown as below.    326       for (j = 0; j < JNXLevelInfo[i].TileCount; j++)
    327         {
    328           PositionList[j].TileBounds.NorthEast.lat = ReadBlobLSBLong(image);
    329           PositionList[j].TileBounds.NorthEast.lon = ReadBlobLSBLong(image);
    330           PositionList[j].TileBounds.SouthWest.lat = ReadBlobLSBLong(image);
    331           PositionList[j].TileBounds.SouthWest.lon = ReadBlobLSBLong(image);
    332           PositionList[j].PicWidth = ReadBlobLSBShort(image);
    333           PositionList[j].PicHeight = ReadBlobLSBShort(image);
    334           PositionList[j].PicSize = ReadBlobLSBLong(image);
    335           PositionList[j].PicOffset = ReadBlobLSBLong(image);
    336         }When a crafted JNX image file, which claims large TileCount but does not contain sufficient backing 
data, is provided,the loop at line 326 would consume huge CPU and memroy resources, since there is no EOF (End of File) 
check inside the loop.In our test, we used a machine with Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz, 4 CPU cores and 
16GB RAM.This bug caused 100% CPU and up to 4GB RAM consumption.This process lasted for about 4 minutes.
Affected version:
1.3.26

Fixed version:
N/A

Commit fix:
http://hg.code.sf.net/p/graphicsmagick/code/rev/b037d79b6ccd
Credit:
This bug was discovered by Xiaohei and Wangchu from Alibaba Security Team.

CVE:
CVE-2017-13775

Reproducer:
https://github.com/shqking/graphicsmagick-poc/blob/master/poc.jnxThe command we was using is     gm convert poc.jnx 
test.jpg

Timeline:
2017-08-24: bug discovered and reported to upstream privately
2017-08-26: upstream released a fix
2017-08-30: CVE assigned