Changeset 40124 for trunk/src/wp-includes/functions.php

Timestamp:

02/25/2017 04:07:25 PM (10 years ago)

Author:

joemcgill

Message:

Media: Reduce failing uploads following 4.7.1.

[39831] introduced more strict MIME type checking for uploads, which
resulted in unintetionally blocking several filetypes that were
previously valid. This change uses a more targeted approach to MIME
validation to restore previous behavior for most types.

Props blobfolio, iandunn, ipstenu, markoheijnen, xknown, joemcgill.
Fixes #39550, #39552.

File:

• trunk/src/wp-includes/functions.php (modified) (3 diffs)

trunk/src/wp-includes/functions.php

@@ -2270 +2270 @@
         }
 
+        $real_mime = false;
+
         // Validate image types.
         if ( $type && 0 === strpos( $type, 'image/' ) ) {
@@ -2276 +2278 @@
                 $real_mime = wp_get_image_mime( $file );
 
-                if ( ! $real_mime ) {
-                        $type = $ext = false;
-                } elseif ( $real_mime != $type ) {
+                if ( $real_mime && $real_mime != $type ) {
                         /**
                          * Filters the list mapping image mime types to their respective extensions.
@@ -2309 +2309 @@
                                 $type = $wp_filetype['type'];
                         } else {
-                                $type = $ext = false;
+                                // Reset $real_mime and try validating again.
+                                $real_mime = false;
                         }
                 }
-        } elseif ( function_exists( 'finfo_file' ) ) {
-                // Use finfo_file if available to validate non-image files.
+        }
+
+        // Validate files that didn't get validated during previous checks.
+        if ( $type && ! $real_mime && extension_loaded( 'fileinfo' ) ) {
                 $finfo = finfo_open( FILEINFO_MIME_TYPE );
                 $real_mime = finfo_file( $finfo, $file );
                 finfo_close( $finfo );
 
-                // If the extension does not match the file's real type, return false.
-                if ( $real_mime !== $type ) {
-                        $type = $ext = false;
+                /*
+                 * If $real_mime doesn't match what we're expecting, we need to do some extra
+                 * vetting of application mime types to make sure this type of file is allowed.
+                 * Other mime types are assumed to be safe, but should be considered unverified.
+                 */
+                if ( $real_mime && ( $real_mime !== $type ) && ( 0 === strpos( $real_mime, 'application' ) ) ) {
+                        $allowed = get_allowed_mime_types();
+
+                        if ( ! in_array( $real_mime, $allowed ) ) {
+                                $type = $ext = false;
+                        }
                 }
         }