[TextFields] Fix character count overflow. (#7255)

Fixes possible overflow when reading out the character count remaining value. Found while testing #7157
material-components · Apr 23, 2019 · 63044ff · 63044ff
1 parent 7b9e9d3
commit 63044ff
Showing 1 changed file with 8 additions and 5 deletions.
diff --git a/components/TextFields/src/MDCTextInputControllerBase.m b/components/TextFields/src/MDCTextInputControllerBase.m
@@ -1486,13 +1486,16 @@ - (void)textInputDidChange:(NSNotification *)note {
 
   // Accessibility
   if (self.textInput.isEditing && self.characterCountMax > 0) {
+    NSUInteger charactersForTextInput =
+        [self.characterCounter characterCountForTextInput:self.textInput];
     NSString *announcementString;
     if (!announcementString.length) {
-      announcementString = [NSString
-          stringWithFormat:@"%lu characters remaining",
-                           (unsigned long)(self.characterCountMax -
-                                           [self.characterCounter
-                                               characterCountForTextInput:self.textInput])];
+      announcementString =
+          [NSString stringWithFormat:@"%lu characters remaining",
+                                     charactersForTextInput > self.characterCountMax
+                                         ? 0U
+                                         : (unsigned long)(MAX(0, self.characterCountMax -
+                                                                      charactersForTextInput))];
     }
 
     // Simply sending a layout change notification does not seem to