Fixed bug #78910

Author: smalyshev

ext/exif/exif.c

@@ -3165,7 +3165,8 @@ static int exif_process_IFD_in_MAKERNOTE(image_info_type *ImageInfo, char * valu
 			continue;
 		if (maker_note->model && (!ImageInfo->model || strcmp(maker_note->model, ImageInfo->model)))
 			continue;
-		if (maker_note->id_string && strncmp(maker_note->id_string, value_ptr, maker_note->id_string_len))
+		if (maker_note->id_string && value_len >= maker_note->id_string_len
+				&& strncmp(maker_note->id_string, value_ptr, maker_note->id_string_len))
 			continue;
 		break;
 	}

ext/exif/tests/bug78910.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Bug #78910: Heap-buffer-overflow READ in exif (OSS-Fuzz #19044)
+--FILE--
+<?php
+
+var_dump(exif_read_data('data:image/jpg;base64,TU0AKgAAAAwgICAgAAIBDwAEAAAAAgAAACKSfCAgAAAAAEZVSklGSUxN'));
+
+?>
+--EXPECTF--
+Notice: exif_read_data(): Read from TIFF: tag(0x927C, MakerNote  ): Illegal format code 0x2020, switching to BYTE in %s on line %d
+
+Warning: exif_read_data(): Process tag(x927C=MakerNote  ): Illegal format code 0x2020, suppose BYTE in %s on line %d
+
+Warning: exif_read_data(): IFD data too short: 0x0000 offset 0x000C in %s on line %d
+
+Warning: exif_read_data(): Invalid TIFF file in %s on line %d
+bool(false)