Memory Leak in png2pnm

[tangyaofang]

issue： #239 unsolved. The same error in the new version 1.6.37：

root@KWE1000859128:/home/test/libpng-1.6.37/contrib/pngminus# ./png2pnm crash_png2pnm_memory_leak 1.pnm
libpng error: Read Error
PNG2PNM
Error: unsuccessful conversion of PNG-image

=================================================================
==100062==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 160 byte(s) in 1 object(s) allocated from:
#0 0x4b8da8 (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4b8da8)
#1 0x4ebb16 (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4ebb16)
#2 0x4eab4d (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4eab4d)
#3 0x7f42e320582f (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)

Indirect leak of 2400 byte(s) in 1 object(s) allocated from:
#0 0x4b8da8 (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4b8da8)
#1 0x4eba76 (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4eba76)
#2 0x4eab4d (/home/test/libpng-1.6.37/contrib/pngminus/png2pnm+0x4eab4d)
#3 0x7f42e320582f (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)

SUMMARY: AddressSanitizer: 2560 byte(s) leaked in 2 allocation(s).

[tangyaofang]

@ctruta :

The issue is:
In the contrib\pngminus\png2pnm.c file, when the png_read_image (png_ptr, row_pointers) statement fails, the previously requested png_pixels row_pointers memory is not released.
I think I have modified this problem and released the requested png_pixels row_pointers memory when an exception is caught.
The following is my modification, please confirm that my modification is correct:

if (setjmp (png_jmpbuf(png_ptr)))
  {
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
    if (row_pointers != NULL)
    {
      free (row_pointers);
      row_pointers = NULL;
    }      
    if (png_pixels != NULL)
    {
      free (png_pixels);
      png_pixels = NULL;
    }      
    return FALSE;
  }

[jbowler]

There is no memory leak here, the program has exited with a fatal error (and this is the correct behavior).