[libpng16] Stop memory leak when returning from png_handle_eXIf() with an error

(Bug report from the OSS-fuzz project).

ANNOUNCE

-Libpng 1.6.32beta03 - August 1, 2017
+Libpng 1.6.32beta03 - August 2, 2017
 
 This is not intended to be a public release. It will be replaced
 within a few weeks by a public version or by another test version.
@@ -39,9 +39,10 @@ Version 1.6.32beta01 [July 31, 2017]
 Version 1.6.32beta02 [August 1, 2017]
   Updated contrib/libtests/pngunknown.c with eXIf chunk.
 
-Version 1.6.32beta03 [August 1, 2017]
+Version 1.6.32beta03 [August 2, 2017]
   Initialized btoa[] in pngstest.c
-  Stop memory leak when returning from png_handle_eXIf() with an error.
+  Stop memory leak when returning from png_handle_eXIf() with an error
+    (Bug report from the OSS-fuzz project).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -5919,12 +5919,13 @@ Version 1.6.32beta01 [July 31, 2017]
     png_set_eXIf_1(), respectively, to avoid breaking API compatibility
     with libpng-1.6.31.
 
-Version 1.6.32beta02 [August 1, 2017]
+Version 1.6.32beta02 [August 2, 2017]
   Updated contrib/libtests/pngunknown.c with eXIf chunk.
 
-Version 1.6.32beta03 [August 1, 2017]
+Version 1.6.32beta03 [August 2, 2017]
   Initialized btoa[] in pngstest.c
-  Stop memory leak when returning from png_handle_eXIf() with an error.
+  Stop memory leak when returning from png_handle_eXIf() with an error
+    (Bug report from the OSS-fuzz project).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

pnginfo.h

@@ -186,8 +186,11 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
 #endif
 
 #ifdef PNG_eXIf_SUPPORTED
-   int num_exif;
+   int num_exif;  /* Added at libpng-1.6.31 */
    png_bytep exif;
+# ifdef PNG_READ_eXIf_SUPPORTED
+   png_bytep eXIf_buf;  /* Added at libpng-1.6.32 */
+# endif
 #endif
 
 #ifdef PNG_hIST_SUPPORTED

pngrutil.c

@@ -2014,6 +2014,7 @@ void /* PRIVATE */
 png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    unsigned int i;
+
    png_bytep eXIf_buf;
 
    png_debug(1, "in png_handle_eXIf");
@@ -2031,18 +2032,25 @@ png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    eXIf_buf = png_voidcast(png_bytep,
              png_malloc_warn(png_ptr, length));
 
+   if (eXIf_buf == NULL)
+   {
+      png_crc_finish(png_ptr, length);
+      png_chunk_benign_error(png_ptr, "out of memory");
+      return;
+   }
+
+   info_ptr->eXIf_buf = eXIf_buf; /* So it will be freed on error */
+   info_ptr->free_me |= PNG_FREE_EXIF;
    for (i = 0; i < length; i++)
    {
       png_byte buf[1];
       png_crc_read(png_ptr, buf, 1);
       eXIf_buf[i] = buf[0];
    }
+   info_ptr->eXIf_buf = NULL;
 
    if (png_crc_finish(png_ptr, 0) != 0)
-   {
-      png_free(png_ptr, eXIf_buf);
       return;
-   }
 
    png_set_eXIf_1(png_ptr, info_ptr, length, eXIf_buf);
 

pngset.c

@@ -146,7 +146,11 @@ png_set_eXIf_1(png_const_structrp png_ptr, png_inforp info_ptr,
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   png_free_data(png_ptr, info_ptr, PNG_FREE_EXIF, 0);
+   if (info_ptr->exif)
+   {
+      png_free(png_ptr, info_ptr->exif);
+      info_ptr->exif = NULL;
+   }
 
    info_ptr->num_exif = num_exif;
 

pngtest.c

@@ -936,8 +936,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       fprintf(STDERR, "%s -> %s: libpng read error\n", inname, outname);
       png_free(read_ptr, row_buf);
       row_buf = NULL;
+      if (verbose != 0)
+        fprintf(STDERR, "   destroy read structs\n");
       png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
 #ifdef PNG_WRITE_SUPPORTED
+      if (verbose != 0)
+        fprintf(STDERR, "   destroy write structs\n");
       png_destroy_info_struct(write_ptr, &write_end_info_ptr);
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
 #endif
@@ -952,11 +956,13 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
    if (setjmp(png_jmpbuf(write_ptr)))
    {
       fprintf(STDERR, "%s -> %s: libpng write error\n", inname, outname);
+      if (verbose != 0)
+        fprintf(STDERR, "   destroying read structs\n");
       png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
+      if (verbose != 0)
+        fprintf(STDERR, "   destroying write structs\n");
       png_destroy_info_struct(write_ptr, &write_end_info_ptr);
-#ifdef PNG_WRITE_SUPPORTED
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
-#endif
       FCLOSE(fpin);
       FCLOSE(fpout);
       return (1);
@@ -1192,16 +1198,19 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
-#ifdef PNG_eXIf_SUPPORTED
+#ifdef PNG_READ_eXIf_SUPPORTED
    {
-      png_bytep exif;
+      png_bytep exif=NULL;
       png_uint_32 exif_length;
 
       if (png_get_eXIf_1(read_ptr, read_info_ptr, &exif_length, &exif) != 0)
       {
-         printf(" eXIf type %c%c, %d bytes\n",exif[0],exif[1],
-            (int)exif_length);
+         if (exif_length > 1)
+            printf(" eXIf type %c%c, %d bytes\n",exif[0],exif[1],
+               (int)exif_length);
+# ifdef PNG_WRITE_eXIf_SUPPORTED
          png_set_eXIf_1(write_ptr, write_info_ptr, exif_length, exif);
+# endif
       }
    }
 #endif
@@ -1547,16 +1556,19 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
-#ifdef PNG_eXIf_SUPPORTED
+#ifdef PNG_READ_eXIf_SUPPORTED
    {
-      png_bytep exif;
+      png_bytep exif=NULL;
       png_uint_32 exif_length;
 
       if (png_get_eXIf_1(read_ptr, end_info_ptr, &exif_length, &exif) != 0)
       {
-         printf(" eXIf type %c%c, %d bytes\n",exif[0],exif[1],
-            (int)exif_length);
+         if (exif_length > 1)
+            printf(" eXIf type %c%c, %d bytes\n",exif[0],exif[1],
+               (int)exif_length);
+# ifdef PNG_WRITE_eXIf_SUPPORTED
          png_set_eXIf_1(write_ptr, write_end_info_ptr, exif_length, exif);
+# endif
       }
    }
 #endif