http://www.embeddedcomputingsystems.com/emag/in_design/1012/docs/SiD_Dec2010.pdf crashes MuPDF due to not taking cliptext calls with accumulate==2 into account and thus underflowing its stack in popclip (which also happens for each cliptext call, not just those with accumulate < 2). Our work-around: http://code.google.com/p/sumatrapdf/source/detail?r=2651
The bug is actually on the other side of the interface -- the interpreter was incorrectly increasing csi->clipdepth when accumulating clipped text continuations. --- old-mupdf-scrub/mupdf/pdf_build.c 2011-02-02 17:37:18.378934628 +0100 +++ new-mupdf-scrub/mupdf/pdf_build.c 2011-02-02 17:37:18.851048391 +0100 @@ -464,7 +464,8 @@ if (doclip) { - gstate->clipdepth++; + if (csi->accumulate < 2) + gstate->clipdepth++; csi->dev->cliptext(csi->dev->user, text, gstate->ctm, csi->accumulate); csi->accumulate = 2; } The above patch fixes the problem.