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Invalid pointer, double free or corruption

I'm reading in many images to do feature extraction and training for an SVM, and I keep getting seemingly random segmentation faults when the code reads in over X images and tries to release a Mat object from a function:

*** glibc detected *** /home/.../build/test: free(): invalid pointer: 0x0000000001bd3100 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x7eb96)[0x7ffff65ceb96]
/home/.../build/test(_ZN2cv3Mat7releaseEv+0x4b)[0x40de29]
/home/.../build/test(_ZN2cv3MatD1Ev+0x18)[0x40dae2]
/home/.../build/test(_Z7getMaskN2cv3MatE+0x798)[0x40c568]
/home/.../build/test(main+0x510)[0x40d0bd]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed)[0x7ffff657176d]
/home/.../build/test[0x40bab9]

.....

(gdb) bt
0  0x00007ffff6586425 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1  0x00007ffff6589b8b in __GI_abort () at abort.c:91
#2  0x00007ffff65c439e in __libc_message (do_abort=2, fmt=0x7ffff66ce008 "*** glibc detected *** %s: %s: 0x%s ***\n")
at ../sysdeps/unix/sysv/linux/libc_fatal.c:201
#3  0x00007ffff65ceb96 in malloc_printerr (action=3, str=0x7ffff66ca913 "free(): invalid pointer", ptr=<optimized out>)
at malloc.c:5018
#4  0x000000000040de29 in cv::Mat::release (this=0x7fffffffd420) at /usr/local/include/opencv2/core/mat.hpp:367
#5  0x000000000040dae2 in cv::Mat::~Mat (this=0x7fffffffd420, __in_chrg=<optimized out>)
at /usr/local/include/opencv2/core/mat.hpp:276
#6  0x000000000040c568 in getMask (input=...) at /home/.../test.cpp:109
#7  0x000000000040d0bd in main (argc=2, argv=0x7fffffffe258) at /home/.../test.cpp:195

test.cpp:109 is the last line of this code block (return finalMask):

Mat getMask(Mat input)
{
  ...
  Mat finalMask;
  const Size ksize(14,14);
  morphologyEx(realMask, finalMask, MORPH_CLOSE, getStructuringElement(MORPH_ELLIPSE, ksize));
  const double thresh = 255.0 / 2.0;
  const double maxval = 255.0;
  threshold(finalMask, finalMask, thresh, maxval, THRESH_BINARY);
  return finalMask;
}

I've been trying to narrow down the problem, but I can't seem to figure it out. In some examples, it fails on consistently on the 423rd image read in. Other times when I changed the code, it failed consistently on the 547th image. Can anyone point me in the right direction to debug this problem?