[Octave-bug-tracker] [bug #61813] memory management bug when calling MEX that returns an output

[Sébastien Villemot]

URL:
  <https://savannah.gnu.org/bugs/?61813>

                 Summary: memory management bug when calling MEX that returns
an output
                 Project: GNU Octave
            Submitted by: svillemot
            Submitted on: jeu. 13 janv. 2022 15:31:35 UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 7.0.90
         Discussion Lock: Any
        Operating System: Any

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Details:

Hi,

I attach a very basic MEX file that triggers a memory management bug
(incorrect memory free). This is a regression in 7.0.90.

The source has to be compiled with:

mkoctfile -mex mexmembug.c


Then, launch Octave within Valgrind:

valgrind octave-cli


When the Octave prompt appears, run:

n = mexmembug;


Then Valgrind prints the following:

==3733875== Mismatched free() / delete / delete []
==3733875==    at 0x484299B: operator delete(void*, unsigned long)
(vg_replace_malloc.c:935)
==3733875==    by 0x50A5F28:
__gnu_cxx::new_allocator<double>::deallocate(double*, unsigned long)
(new_allocator.h:145)
==3733875==    by 0x50A5E25: std::allocator_traits<std::allocator<double>
>::deallocate(std::allocator<double>&, double*, unsigned long)
(alloc_traits.h:496)
==3733875==    by 0x50A5CC1: Array<double, std::allocator<double>
>::ArrayRep::deallocate(double*, unsigned long) (Array.h:207)
==3733875==    by 0x50A5BB8: Array<double, std::allocator<double>
>::ArrayRep::~ArrayRep() (Array.h:187)
==3733875==    by 0x50A59C7: Array<double, std::allocator<double> >::~Array()
(Array.h:356)
==3733875==    by 0x5AF2580: octave_value
mxArray_base_full::fp_to_ov<double>(dim_vector const&) const (mex.cc:2177)
==3733875==    by 0x5AEDE06: mxArray_base_full::as_octave_value() const
(mex.cc:2084)
==3733875==    by 0x5AEED5D: mxArray_separate_full::as_octave_value() const
(mex.cc:2411)
==3733875==    by 0x5AE1FDD: mxArray::as_octave_value() const (mex.cc:3242)
==3733875==    by 0x5AE1F18: mxArray::as_octave_value(mxArray const*, bool)
(mex.cc:3236)
==3733875==    by 0x5AE4CAB: call_mex(octave_mex_function&, octave_value_list
const&, int) (mex.cc:4785)
==3733875==  Address 0x4705de10 is 0 bytes inside a block of size 8 alloc'd
==3733875==    at 0x483F7B5: malloc (vg_replace_malloc.c:381)
==3733875==    by 0x5AE1617: xmalloc(unsigned long) (mex.cc:270)
==3733875==    by 0x5AF1769: mex::malloc_unmarked(unsigned long)
(mex.cc:3414)
==3733875==    by 0x5AF182A: mex::calloc_unmarked(unsigned long, unsigned
long) (mex.cc:3441)
==3733875==    by 0x5AE2713: mxArray::calloc(unsigned long, unsigned long)
(mex.cc:3686)
==3733875==    by 0x5AED2C5: mxArray_base_full::mxArray_base_full(bool,
mxClassID, double) (mex.cc:1653)
==3733875==    by 0x5AEE65E:
mxArray_separate_full::mxArray_separate_full(mxClassID, double) (mex.cc:2321)
==3733875==    by 0x5AE22F1: mxArray::create_rep(bool, mxClassID, double)
(mex.cc:3287)
==3733875==    by 0x5AE1949: mxArray::mxArray(bool, mxClassID, double)
(mex.cc:3164)
==3733875==    by 0x5AE304C: mxCreateDoubleScalar (mex.cc:3895)
==3733875==    by 0x709B135: mexFunction (mexmembug.c:10)
==3733875==    by 0x5AE4C0A: call_mex(octave_mex_function&, octave_value_list
const&, int) (mex.cc:4769)






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File Attachments:


-------------------------------------------------------
Date: jeu. 13 janv. 2022 15:31:35 UTC  Name: mexmembug.c  Size: 254o   By:
svillemot

<http://savannah.gnu.org/bugs/download.php?file_id=52659>

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