Subject: [UMN_MAPSERVER-USERS] Important! 1 pixel anti-aliasing seg. faults...
Newsgroups: gmane.comp.gis.mapserver.user
Date: 2006-02-14 17:35:43 GMT (2 years, 13 weeks, 19 hours and 15 minutes ago)
Hi all: There have been a number of users reporting issues with 1 pixel wide antialiasing seg. faults and version 4.8. There is a problem with GD. The library does not properly check pixel values against the image size which can result in a buffer overflow in some cases. The GD author is aware of the problem but has not released a fix yet- no idea why since it is a pretty severe error. Anyway, to use 1 pixel-wide antialiasing you *MUST* apply a small fix to GD. Fortunately the fix is a one-liner. In gd.c, function gdImageSetAAPixelColor() change: int dr,dg,db,p,r,g,b; p = gdImageGetPixel(im,x,y); to: int dr,dg,db,p,r,g,b; if (!gdImageBoundsSafeMacro (im, x, y)) return; p = gdImageGetPixel(im,x,y); I can put together a patch version of the gd-2.033 source if folks are interested. Steve