Changeset 40134 for branches/4.7/src/wp-includes/functions.php

Timestamp:

02/27/2017 07:27:58 PM (8 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.
Merges [40124] and [40125] to the 4.7 branch.
Fixes #39550, #39552.

Location:

branches/4.7

Files:

• . (modified) (1 prop)
• src/wp-includes/functions.php (modified) (3 diffs)

branches/4.7/src/wp-includes/functions.php

@@ -2269 +2269 @@
     }
 
+    $real_mime = false;
+
     // Validate image types.
     if ( $type && 0 === strpos( $type, 'image/' ) ) {
@@ -2275 +2277 @@
         $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.
@@ -2308 +2308 @@
                 $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;
+            }
         }
     }