Bugzilla – Bug 691876
typo in imagesmooth.c ?
Last modified: 2011-01-17 11:46:40 UTC
Could http://code.google.com/p/sumatrapdf/source/diff?spec=svn2625&r=2625&format=side&path=/trunk/mupdf/draw/imagesmooth.c#sc_svn2614_928 be a typo? It's currently apparently possible for min to become less than src_w at line 928 which leads to a negative index at line 934 and thus a potential read access violation. Making that change didn't even regress anything in my test suite.
No, it's correct as is - or at least should be.
It shouldn't be possible for min to be less than src_w. If it is, then there is clearly something going on that I haven't considered.
If you are in a position to reproduce the crash, I'd very much like to know the values of the arguments to scale_single_col (and the values of the members of weights).
Or even better, build with 'DEBUG_SCALING' defined and get me a dump of the output for the scale operation that crashes.
Created attachment 7116 [details]
The attached dump has been produced while rendering the first page of the document downloadable from http://code.google.com/p/sumatrapdf/issues/detail?id=1162 .
BTW: You should be able to reproduce the potential read access violation yourself, even if it doesn't lead to a crash: just set a conditional breakpoint at line 928 on "(src_w-min)*n>src_w".
Having looked more closely at the code, I do:
src_w = (src_w-1)*n;
earlier, hence src_w has already been multiplied by n. You are therefore absolutely correct, and I shouldn't be multiplying src_w by n again. Your fix was ideal. I've asked Tor to push it to the repo.
Thanks for this!
Tor has now recorded this patch, so closing. Thanks all.