• API PyDict_SetItemString does not steal a reference from the third argument.
• API PyDict_SetItem does not steal a reference from the last argument.
• API PyList_Append does not steal a reference from the second argument.
• API PyDict_SetItem does not steal a reference from the third argument if the return value is not zero.

If a new reference is passed to the function without decreasing its refcnt then, it will lead to a memory leak.

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Pattern 1: APIs returning a new reference are called directly as the third argument.

• Internal Report ID: 1b7403
  

  Pillow/src/_imaging.c

  Line 3773 in 68e39cb

  PyDict_SetItemString(d, "new_count", PyLong_FromLong(arena->stats_new_count));

• Internal Report ID: 6fa78e
  

  Pillow/src/_imaging.c

  Line 3775 in 68e39cb

  d, "allocated_blocks", PyLong_FromLong(arena->stats_allocated_blocks));

• Internal Report ID: b43c87
  

  Pillow/src/_imaging.c

  Line 3777 in 68e39cb

  d, "reused_blocks", PyLong_FromLong(arena->stats_reused_blocks));

• Internal Report ID: 1640ab
  

  Pillow/src/_imaging.c

  Line 3779 in 68e39cb

  d, "reallocated_blocks", PyLong_FromLong(arena->stats_reallocated_blocks));

• Internal Report ID: 78d881
  

  Pillow/src/_imaging.c

  Line 3780 in 68e39cb

  PyDict_SetItemString(d, "freed_blocks", PyLong_FromLong(arena->stats_freed_blocks));

• Internal Report ID: 6acded
  

  Pillow/src/_imaging.c

  Line 3781 in 68e39cb

  PyDict_SetItemString(d, "blocks_cached", PyLong_FromLong(arena->blocks_cached));

• Internal Report ID: 15cbc4
  

  Pillow/src/_imaging.c

  Line 4154 in 68e39cb

  d, "jpeglib_version", PyUnicode_FromString(ImagingJpegVersion()));

• Internal Report ID: a78d30
  

  Pillow/src/_imaging.c

  Line 4162 in 68e39cb

  d, "jp2klib_version", PyUnicode_FromString(ImagingJpeg2KVersion()));

• Internal Report ID: 446850
  

  Pillow/src/_imaging.c

  Line 4172 in 68e39cb

  d, "libjpeg_turbo_version", PyUnicode_FromString(tostr(LIBJPEG_TURBO_VERSION)));

• Internal Report ID: 3c8041
  

  Pillow/src/_imaging.c

  Line 4187 in 68e39cb

  d, "imagequant_version", PyUnicode_FromString(ImagingImageQuantVersion()));

• Internal Report ID: 1abe89
  

  Pillow/src/_imaging.c

  Line 4205 in 68e39cb

  d, "zlib_version", PyUnicode_FromString(ImagingZipVersion()));

• Internal Report ID: b9e74a
  

  Pillow/src/_imaging.c

  Line 4213 in 68e39cb

  d, "libtiff_version", PyUnicode_FromString(ImagingTiffVersion()));

• Internal Report ID: be23b5
  

  Pillow/src/_imaging.c

  Line 4236 in 68e39cb

  PyDict_SetItemString(d, "PILLOW_VERSION", PyUnicode_FromString(version));

• Internal Report ID: 611fdf
  

  Pillow/src/_imagingft.c

  Line 1120 in 68e39cb

  list_axis, "minimum", PyLong_FromLong(axis.minimum / 65536));

• Internal Report ID: 7c0d23
  

  Pillow/src/_imagingft.c

  Line 1121 in 68e39cb

  PyDict_SetItemString(list_axis, "default", PyLong_FromLong(axis.def / 65536));

• Internal Report ID: b84747
  

  Pillow/src/_imagingft.c

  Line 1123 in 68e39cb

  list_axis, "maximum", PyLong_FromLong(axis.maximum / 65536));

• Internal Report ID: 3c802a
  

  Pillow/src/_imagingmorph.c

  Line 243 in 68e39cb

  PyDict_SetItemString(d, "__version", PyUnicode_FromString("0.1"));

• Internal Report ID: 71bbbc
  

  Pillow/src/_webp.c

  Line 960 in 68e39cb

  d, "webpdecoder_version", PyUnicode_FromString(WebPDecoderVersion_str()));

• Internal Report ID: 213466
  

  Pillow/src/_webp.c

  Line 949 in 68e39cb

  m, "HAVE_TRANSPARENCY", PyBool_FromLong(!WebPDecoderBuggyAlpha()));

Pattern 2: Intermediate variables are used to forward the argument.

• Internal Report ID: e4a37b

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: dc5fd5

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: 1e988b

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: 0ef1f7

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: fce490

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: d17f14

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: 21a68f

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: e80f52

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: 29a870

New reference is returned here:

PyObject is passed to non-stealing API here:

---

• Internal Report ID: fddf55

New reference is returned here:

PyObject is passed to non-stealing API here: