Returns an error immediately without sending IPC message when a font family name to resolve is too long.

This change is important when a site has @font-face rule like:

  // http://paulirish.com/webkit-fontface-hang.html
  @font-face{font-family:testfont;src:url('data:font/ttf;base64,AA.....<<looooooooooong base64 data>>.....aQ==')}

In such a case, WebCore first calls SkFontHost::CreateTypeface() with the (possibly very long) data-uri string itself, then calls SkFontHost::CreateTypefaceFromStream() with decoded byte stream. Since render_sandbox_host_linux.cc just ignores too long IPC message, the renderer process could block indefinitely waiting for a reply inside recvmsg() system call called from SkFontHost::CreateTypeface().

I'm not sure if the WebCore behavior (i.e. calling CreateTypeface with data-uris) is reasonable, but I believe the Skia part is better to be fixed anyway. Non data-uri font family names could be very long too:

  @font-face{font-family:testfont;src:local('AA........AA');}

BUG=29861
TEST=First, set up your Linux SUID Sandbox binary: http://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment. Then start Chromium and visit http://paulirish.com/webkit-fontface-hang.html or http://typekit.com/. Verify that the renderer does not freeze.

Review URL: http://codereview.chromium.org/507037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34915 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 3 insertions, 0 deletions

diff --git a/skia/ext/SkFontHost_fontconfig_direct.cpp b/skia/ext/SkFontHost_fontconfig_direct.cpp
index 3f19fc7..9434f51 100644
--- a/skia/ext/SkFontHost_fontconfig_direct.cpp
+++ b/skia/ext/SkFontHost_fontconfig_direct.cpp
@@ -46,6 +46,9 @@ bool FontConfigDirect::Match(std::string* result_family,
                              bool fileid_valid, unsigned fileid,
                              const std::string& family, bool* is_bold,
                              bool* is_italic) {
+    if (family.length() > kMaxFontFamilyLength)
+        return false;
+
     SkAutoMutexAcquire ac(mutex_);
     FcPattern* pattern = FcPatternCreate();