Bug#723067: Vertical gradient on element with height >64k pixels causes page to stop scrolling/rerendering

Josh Triplett josh at joshtriplett.org
Mon Sep 16 02:35:39 UTC 2013


Package: iceweasel
Version: 24.0~b9-1
Severity: normal
Tags: upstream

I've attached a minimal test page, which applies a vertical linear
gradient to the body.  The body contains several thousand paragraphs,
and as a result takes up more than 64k pixels of height.  If I attempt
to scroll this page to the bottom, either by pressing end or by holding
down page-down, the scrolling stops somewhere in the middle, right
around the 64k pixel mark.  Once scrolling stops, the page no longer
responds to any attempt to scroll with either the keyboard or the
scrollbar.  Force-refreshing the page returns to the top.

This depends specifically on rendered height: if I increase or decrease
the font size, the point at which scrolling freezes will move up or down
in the text accordingly.  If I decrease the font size enough, I can
reach the bottom of the page without triggering the problem.  The freeze
doesn't always occur at exactly the same location, but generally within
a few dozen lines of the 64k pixel mark.

I can reproduce this scroll freeze 100% reliably with this test case.

The test case seems oddly fragile in a few ways.  If I drastically
increase the font size on the html element (for instance, going to
50px), the problem goes away, but the gradient still mis-renders in many
places in the page (restarting, or showing a solid color).  If I replace
the relative 1.1em font-size on body with an absolute one, even one
resulting in about the same size, I see the same behavior: no scrolling
issue, but a mis-rendered gradient.

Reported upstream as https://bugzilla.mozilla.org/show_bug.cgi?id=916624
, but I've reported it here as well because it may specifically occur
with Debian's build that uses system graphics libraries.  Two testers
using upstream builds said they could not reproduce the scroll freeze,
though they could observe incorrect gradient rendering.

I can reproduce this in safe mode, so it doesn't depend on configuration
or extensions.

- Josh Triplett

-- Package-specific info:

-- Extensions information
Name: Adblock Plus
Location: /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/{d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}
Package: xul-ext-adblock-plus
Status: enabled

Name: Default theme
Location: /usr/lib/iceweasel/browser/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}
Package: iceweasel
Status: enabled

Name: Firebug
Location: /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/firebug at software.joehewitt.com
Package: xul-ext-firebug
Status: enabled

Name: HTTPS-Everywhere
Location: /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/https-everywhere at eff.org
Package: xul-ext-https-everywhere
Status: enabled

Name: It's All Text!
Location: /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/itsalltext at docwhat.gerf.org
Package: xul-ext-itsalltext
Status: enabled

-- Plugins information
Name: Gnome Shell Integration
Location: /usr/lib/mozilla/plugins/libgnome-shell-browser-plugin.so
Package: gnome-shell
Status: enabled

Name: iTunes Application Detector
Location: /usr/lib/mozilla/plugins/librhythmbox-itms-detection-plugin.so
Package: rhythmbox-plugins
Status: enabled


-- Addons package information
ii  gnome-shell    3.4.2-15+b1  amd64        graphical shell for the GNOME des
ii  iceweasel      24.0~b9-1    amd64        Web browser based on Firefox
ii  rhythmbox-plug 2.99.1-3     amd64        plugins for rhythmbox music playe
ii  xul-ext-adbloc 2.3.2-1      all          advertisement blocking extension 
ii  xul-ext-firebu 1.12.1-2     all          web development plugin for Icewea
ii  xul-ext-https- 3.4.1-1      all          extension to force the use of HTT
ii  xul-ext-itsall 1.8.1-1      all          extension to edit textareas using

-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 3.10-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages iceweasel depends on:
ii  debianutils         4.4
ii  fontconfig          2.10.2-2
ii  libc6               2.17-92+b1
ii  libgdk-pixbuf2.0-0  2.28.2-1
ii  libglib2.0-0        2.36.4-1
ii  libgtk2.0-0         2.24.20-1
ii  libnspr4            2:4.10-1
ii  libnspr4-0d         2:4.10-1
ii  libsqlite3-0        3.8.0.2-1
ii  libstdc++6          4.8.1-10
ii  procps              1:3.3.8-2
ii  xulrunner-24.0      24.0~b9-1

iceweasel recommends no packages.

Versions of packages iceweasel suggests:
pn  fonts-mathjax          <none>
pn  fonts-oflb-asana-math  <none>
pn  fonts-stix | otf-stix  <none>
ii  libgssapi-krb5-2       1.11.3+dfsg-3
pn  mozplugger             <none>

Versions of packages xulrunner-24.0 depends on:
ii  libasound2                1.0.27.2-1
ii  libatk1.0-0               2.8.0-2
ii  libbz2-1.0                1.0.6-5
ii  libc6                     2.17-92+b1
ii  libcairo2                 1.12.16-1
ii  libdbus-1-3               1.6.14-1
ii  libdbus-glib-1-2          0.100.2-1
ii  libevent-2.0-5            2.0.21-stable-1
ii  libfontconfig1            2.10.2-2
ii  libfreetype6              2.4.9-1.1
ii  libgcc1                   1:4.8.1-10
ii  libgdk-pixbuf2.0-0        2.28.2-1
ii  libglib2.0-0              2.36.4-1
ii  libgtk2.0-0               2.24.20-1
ii  libhunspell-1.3-0         1.3.2-4
ii  libmozjs24d               24.0~b9-1
ii  libnspr4                  2:4.10-1
ii  libnss3                   2:3.15.1-1
ii  libpango-1.0-0            1.32.5-5+b1
ii  libpixman-1-0             0.30.2-1
ii  libsqlite3-0              3.8.0.2-1
ii  libstartup-notification0  0.12-3
ii  libstdc++6                4.8.1-10
ii  libvpx1                   1.2.0-2
ii  libx11-6                  2:1.6.1-1
ii  libxext6                  2:1.3.2-1
ii  libxrender1               1:0.9.8-1
ii  libxt6                    1:1.1.4-1
ii  zlib1g                    1:1.2.8.dfsg-1

Versions of packages xulrunner-24.0 suggests:
ii  libcanberra0  0.30-2
ii  libgnomeui-0  2.24.5-2

-- no debconf information
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