tor-browser

commit a775b2c4830edf8bbafdf9637959af0e228ecb98
parent f3904f706bc928c63a9ab3e7b185e749ed40d6d9
Author: agoloman <agoloman@mozilla.com>
Date:   Fri, 21 Nov 2025 22:12:57 +0200

Revert "Bug 736194 - Clamp tab title length to a reasonable number to prevent hangs r=tabbrowser-reviewers,nsharpley,dao" for causing dt failures @browser_accessibility_print_to_json.js.

This reverts commit b8f0363af1bc67c50e661a675bf4fb3cf2d99fce.

Diffstat:
M
browser/components/tabbrowser/content/tabbrowser.js
 | 
6
------
M
browser/components/tabbrowser/test/browser/tabs/browser.toml
 | 
3
---
D
browser/components/tabbrowser/test/browser/tabs/browser_tab_label_character_cap.js
 | 
58
----------------------------------------------------------

3 files changed, 0 insertions(+), 67 deletions(-)
diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
@@ -30,7 +30,6 @@
 
   const DIRECTION_FORWARD = 1;
   const DIRECTION_BACKWARD = -1;
-  const TAB_LABEL_MAX_LENGTH = 256;
 
   /**
    * Updates the User Context UI indicators if the browser is in a non-default context
@@ -1982,11 +1981,6 @@
         aLabel = aLabel.replace(this._regex_shortenURLForTabLabel, "");
       }
 
-      if (aLabel.length > TAB_LABEL_MAX_LENGTH) {
-        // Clamp overly-long titles to avoid DoS-type hangs (bug 736194).
-        aLabel = aLabel.substring(0, TAB_LABEL_MAX_LENGTH);
-      }
-
       aTab._labelIsContentTitle = isContentTitle;
 
       if (aTab.getAttribute("label") == aLabel) {
diff --git a/browser/components/tabbrowser/test/browser/tabs/browser.toml b/browser/components/tabbrowser/test/browser/tabs/browser.toml
@@ -183,9 +183,6 @@ skip-if = [
 ["browser_long_data_url_label_truncation.js"]
 tags = "vertical-tabs"
 
-["browser_tab_label_character_cap.js"]
-tags = "vertical-tabs"
-
 ["browser_middle_click_new_tab_button_loads_clipboard.js"]
 tags = "vertical-tabs"
 fail-if =  ["vertical_tab"] # Bug 1932787, fails in the "vertical-tabs" variant
diff --git a/browser/components/tabbrowser/test/browser/tabs/browser_tab_label_character_cap.js b/browser/components/tabbrowser/test/browser/tabs/browser_tab_label_character_cap.js
@@ -1,58 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
-   http://creativecommons.org/publicdomain/zero/1.0/ */
-
-"use strict";
-
-/**
- * Ensure that setTabTitle clamps very long document titles to 255 characters
- * so malicious pages cannot hang the browser by forcing us to lay out absurdly
- * large tab labels.
- */
-add_task(async function test_tab_label_is_capped_at_255_chars() {
-  const LONG_TITLE_LENGTH = 257;
-  const EXPECTED_LABEL_LENGTH = 256;
-  const TITLE_CHAR = "A";
-
-  await BrowserTestUtils.withNewTab("about:blank", async browser => {
-    const tab = gBrowser.getTabForBrowser(browser);
-
-    const fullTitleLength = await SpecialPowers.spawn(
-      browser,
-      [LONG_TITLE_LENGTH, TITLE_CHAR],
-      (length, character) => {
-        content.document.title = character.repeat(length);
-        return content.document.title.length;
-      }
-    );
-    Assert.equal(
-      fullTitleLength,
-      LONG_TITLE_LENGTH,
-      "Sanity check: content received the full title"
-    );
-
-    await BrowserTestUtils.waitForCondition(
-      () => tab.label.length === EXPECTED_LABEL_LENGTH,
-      "Tab label should be clamped"
-    );
-
-    Assert.equal(
-      tab.label.length,
-      EXPECTED_LABEL_LENGTH,
-      "Displayed label is capped at 256 characters"
-    );
-    Assert.equal(
-      tab.label,
-      TITLE_CHAR.repeat(EXPECTED_LABEL_LENGTH),
-      "Tab label matches the first 256 title characters"
-    );
-
-    const reportedTitleLength = await SpecialPowers.spawn(browser, [], () => {
-      return content.document.title.length;
-    });
-    Assert.equal(
-      reportedTitleLength,
-      LONG_TITLE_LENGTH,
-      "document.title remains unchanged"
-    );
-  });
-});