Getting a `free()` error when deallocating with `delete` in the backtrace - c++

Question

I got the following error from gdb:
*** glibc detected *** /.root0/autohome/u132/hsreekum/ipopt/ipopt/debug/Ipopt/examples/ex3/ex3: free(): invalid next size (fast): 0x0000000120052b60 ***
Here's the backtrace:
#0 0x000000555626b264 in raise () from /lib/libc.so.6
#1 0x000000555626cc6c in abort () from /lib/libc.so.6
#2 0x00000055562a7b9c in __libc_message () from /lib/libc.so.6
#3 0x00000055562aeabc in malloc_printerr () from /lib/libc.so.6
#4 0x00000055562b036c in free () from /lib/libc.so.6
#5 0x000000555561ddd0 in Ipopt::TNLPAdapter::~TNLPAdapter ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#6 0x00000055556a9910 in Ipopt::GradientScaling::~GradientScaling ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#7 0x00000055557241b8 in Ipopt::OrigIpoptNLP::~OrigIpoptNLP ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#8 0x00000055556ae7f0 in Ipopt::IpoptAlgorithm::~IpoptAlgorithm ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#9 0x0000005555602278 in Ipopt::IpoptApplication::~IpoptApplication ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#10 0x0000005555614428 in FreeIpoptProblem ()
from /home/ba01/u132/hsreekum/ipopt/ipopt/build/lib/libipopt.so.1
#11 0x0000000120001610 in main () at ex3.c:169`
And here's the code for Ipopt::TNLPAdapter::~TNLPAdapter ()
TNLPAdapter::~TNLPAdapter()
{
delete [] full_x_;
delete [] full_lambda_;
delete [] full_g_;
delete [] jac_g_;
delete [] c_rhs_;
delete [] jac_idx_map_;
delete [] h_idx_map_;
delete [] x_fixed_map_;
delete [] findiff_jac_ia_;
delete [] findiff_jac_ja_;
delete [] findiff_jac_postriplet_;
delete [] findiff_x_l_;
delete [] findiff_x_u_;
}
My question is : why does free() throw an error when ~TNLPAdapter() uses delete[]? Also, I would like to step through ~TNLPAdapter() so I can see which deallocation causes the error. I believe the error occurs in the external library (IPOPT) but I have compiled it with debug flags on ; is this sufficient?

Answer 1

Raw memory allocation/deallocation mechanism behind new[]/delete[] is typically the same as the one used by malloc/free. Standard library implementation of raw memory allocation/deallocation functions operator new[]/operator delete[] can actually directly call malloc and free. For this reason, it is completely unsurprising that the error is reported by free even if you are using delete [].
The error that you are getting indicates that the integrity of heap is violated. The heap is broken. The source of the problem can be in this function (double free?) or in some completely different place (double free or memory overrun?). There's no way to say what is happening from the code you posted.
Figure out which specific call to delete [] reports the problem and see if some other code overrides that memory block. Or just use some external tool like valgrind to catch the offender.