2003.06.26 21:08 "Bug located in Sam Leffler's thumbnail.c", by Robert S. Kissel
The bugzilla.remotesensing.org facility doesn't seem to respond.
There's a bug in the file thumbnail.c (which serves as one of the application examples), namely, _TIFFfree is never called to release memory in the function "generateThumbnail."
It probably has gone unnoticed until now because nobody has used the code, before me, to thumbnail an extremely large number of IFD's in a single file.
If anybody can get Mr. Leffler in touch with me, I'll answer any questions he has about the problem, but I think he'll see what needs to be repaired if he reads this post.
I downloaded my copy of the source in late February or March, so I doubt if it has been corrected since.