Apparently there is a change coming in glibc which can trigger silent data corruption bugs in existing software that misuses memcpy with overlapping regions. http://lwn.net/Articles/414467/#Comments
Perhaps alpha versions of Natty or Natty+1 should test for this (using LD_PRELOAD or a modified glibc), and emit a backtrace to apport when memcpy is called with overlapping regions? This would reduce performance somewhat, but alpha versions are for finding bugs, not running fast. Even though testing for overlapping regions could take a large part of the time taken by small memcpy's, apparently less than 1% of time is typically in memcpy, so this shouldn't have a significant effect on system-wide performance. Valgrind also emits this warning, but it seems important that this gets widespread testing, and even in alpha versions running everything under Valgrind by default is not acceptable. -- John C. McCabe-Dansted
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