1717654 - Assertion failure: firstStop >= 0.0 (Failed to fix stop offsets), at /builds/worker/checkouts/gecko/layout/painting/nsCSSRenderingGradients.cpp:851

Status: NEW

(Core :: Web Painting, defect, P3)

Description

[Jason Kratzer [:jkratzer]]

Attachment: testcase.html

Testcase found while fuzzing mozilla-central rev 997f00815e6b (built with --enable-debug --enable-fuzzing).

Testcase can be reproduced using the following commands:

$ pip install fuzzfetch grizzly-framework
$ python -m fuzzfetch --build 997f00815e6b --debug --fuzzing -n mc-debug
$ python -m grizzly.replay ./mc-debug/firefox ./testcase.html

Assertion failure: firstStop >= 0.0 (Failed to fix stop offsets), at /builds/worker/checkouts/gecko/layout/painting/nsCSSRenderingGradients.cpp:851

    #0 0x7fcc8665635b in mozilla::nsCSSGradientRenderer::Paint(gfxContext&, nsRect const&, nsRect const&, nsSize const&, mozilla::gfx::IntRectTyped<mozilla::CSSPixel> const&, nsRect const&, float) /builds/worker/checkouts/gecko/layout/painting/nsCSSRenderingGradients.cpp:851:5
    #1 0x7fcc866a8690 in mozilla::nsImageRenderer::Draw(nsPresContext*, gfxContext&, nsRect const&, nsRect const&, nsRect const&, nsPoint const&, nsSize const&, mozilla::gfx::IntRectTyped<mozilla::CSSPixel> const&, float) /builds/worker/checkouts/gecko/layout/painting/nsImageRenderer.cpp:494:16
    #2 0x7fcc866aa1dd in mozilla::nsImageRenderer::DrawBorderImageComponent(nsPresContext*, gfxContext&, nsRect const&, nsRect const&, mozilla::gfx::IntRectTyped<mozilla::CSSPixel> const&, mozilla::StyleBorderImageRepeat, mozilla::StyleBorderImageRepeat, nsSize const&, unsigned char, mozilla::Maybe<nsSize> const&, bool) /builds/worker/checkouts/gecko/layout/painting/nsImageRenderer.cpp:999:10
    #3 0x7fcc86639777 in nsCSSBorderImageRenderer::DrawBorderImage(nsPresContext*, gfxContext&, nsIFrame*, nsRect const&) /builds/worker/checkouts/gecko/layout/painting/nsCSSRenderingBorders.cpp:3552:32
    #4 0x7fcc8663746d in nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext*, gfxContext&, nsIFrame*, nsRect const&, nsRect const&, nsStyleBorder const&, mozilla::ComputedStyle*, mozilla::PaintBorderFlags, mozilla::Sides) /builds/worker/checkouts/gecko/layout/painting/nsCSSRendering.cpp:857:24
    #5 0x7fcc86637144 in nsCSSRendering::PaintBorder(nsPresContext*, gfxContext&, nsIFrame*, nsRect const&, nsRect const&, mozilla::ComputedStyle*, mozilla::PaintBorderFlags, mozilla::Sides) /builds/worker/checkouts/gecko/layout/painting/nsCSSRendering.cpp:649:10
    #6 0x7fcc8666fca6 in nsDisplayBorder::Paint(nsDisplayListBuilder*, gfxContext*) /builds/worker/checkouts/gecko/layout/painting/nsDisplayList.cpp:5140:26
    #7 0x7fcc82e88e4f in mozilla::layers::PaintItemByDrawTarget(nsDisplayItem*, mozilla::gfx::DrawTarget*, mozilla::gfx::PointTyped<mozilla::LayoutDevicePixel, float> const&, mozilla::gfx::IntRectTyped<mozilla::gfx::UnknownUnits> const&, nsDisplayListBuilder*, mozilla::gfx::SizeTyped<mozilla::gfx::UnknownUnits, float> const&, mozilla::Maybe<mozilla::gfx::DeviceColor>&) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:2003:38
    #8 0x7fcc82e88143 in mozilla::layers::WebRenderCommandBuilder::GenerateFallbackData(nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, nsDisplayListBuilder*, mozilla::gfx::RectTyped<mozilla::LayoutDevicePixel, float>&) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:2272:7
    #9 0x7fcc82e83bb1 in mozilla::layers::WebRenderCommandBuilder::PushItemAsImage(nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, nsDisplayListBuilder*) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:2570:48
    #10 0x7fcc82e8218e in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList*, nsDisplayItem*, nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:1791:7
    #11 0x7fcc8667706c in CreateWebRenderCommands /builds/worker/checkouts/gecko/layout/painting/nsDisplayList.cpp:5700:30
    #12 0x7fcc8667706c in nsDisplayOwnLayer::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, nsDisplayListBuilder*) /builds/worker/checkouts/gecko/layout/painting/nsDisplayList.cpp:6514:22
    #13 0x7fcc82e83a7b in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, nsDisplayListBuilder*) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:1668:41
    #14 0x7fcc82e8218e in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList*, nsDisplayItem*, nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:1791:7
    #15 0x7fcc82e80ef2 in mozilla::layers::WebRenderCommandBuilder::BuildWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, nsDisplayList*, nsDisplayListBuilder*, mozilla::layers::WebRenderScrollData&, WrFiltersHolder&&) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderCommandBuilder.cpp:1588:5
    #16 0x7fcc82eab8b4 in mozilla::layers::WebRenderLayerManager::EndTransactionWithoutLayer(nsDisplayList*, nsDisplayListBuilder*, WrFiltersHolder&&, mozilla::layers::WebRenderBackgroundData*, double) /builds/worker/checkouts/gecko/gfx/layers/wr/WebRenderLayerManager.cpp:368:30
    #17 0x7fcc86661948 in nsDisplayList::PaintRoot(nsDisplayListBuilder*, gfxContext*, unsigned int, mozilla::Maybe<double>) /builds/worker/checkouts/gecko/layout/painting/nsDisplayList.cpp:2540:18
    #18 0x7fcc862ca242 in nsLayoutUtils::PaintFrame(gfxContext*, nsIFrame*, nsRegion const&, unsigned int, nsDisplayListBuilderMode, nsLayoutUtils::PaintFrameFlags) /builds/worker/checkouts/gecko/layout/base/nsLayoutUtils.cpp:3530:45
    #19 0x7fcc862428e7 in mozilla::PresShell::Paint(nsView*, nsRegion const&, mozilla::PaintFlags) /builds/worker/checkouts/gecko/layout/base/PresShell.cpp:6383:5
    #20 0x7fcc85eeda71 in nsViewManager::ProcessPendingUpdatesPaint(nsIWidget*) /builds/worker/checkouts/gecko/view/nsViewManager.cpp:459:18
    #21 0x7fcc85eed58b in nsViewManager::ProcessPendingUpdatesForView(nsView*, bool) /builds/worker/checkouts/gecko/view/nsViewManager.cpp:394:22
    #22 0x7fcc85eeeaff in nsViewManager::ProcessPendingUpdates() /builds/worker/checkouts/gecko/view/nsViewManager.cpp:972:5
    #23 0x7fcc862015b8 in nsRefreshDriver::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsRefreshDriver::IsExtraTick) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:2476:11
    #24 0x7fcc862088ba in TickDriver /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:348:13
    #25 0x7fcc862088ba in mozilla::RefreshDriverTimer::TickRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsTArray<RefPtr<nsRefreshDriver> >&) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:326:7
    #26 0x7fcc862087d3 in mozilla::RefreshDriverTimer::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:342:5
    #27 0x7fcc862086a0 in mozilla::VsyncRefreshDriverTimer::RunRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:775:5
    #28 0x7fcc86207d08 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::TickRefreshDriver(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:704:16
    #29 0x7fcc862075f0 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyParentProcessVsync() /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:617:7
    #30 0x7fcc86207069 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyVsync(mozilla::VsyncEvent const&) /builds/worker/checkouts/gecko/layout/base/nsRefreshDriver.cpp:538:9
    #31 0x7fcc85a28446 in mozilla::dom::VsyncChild::RecvNotify(mozilla::VsyncEvent const&, float const&) /builds/worker/checkouts/gecko/dom/ipc/VsyncChild.cpp:68:15
    #32 0x7fcc8272d300 in mozilla::dom::PVsyncChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PVsyncChild.cpp:178:54
    #33 0x7fcc824f731c in mozilla::ipc::PBackgroundChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PBackgroundChild.cpp:6091:32
    #34 0x7fcc82179ec1 in mozilla::ipc::MessageChannel::DispatchAsyncMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message const&) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:2148:25
    #35 0x7fcc82176271 in mozilla::ipc::MessageChannel::DispatchMessage(IPC::Message&&) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:2075:9
    #36 0x7fcc821777ad in mozilla::ipc::MessageChannel::RunMessage(mozilla::ipc::MessageChannel::MessageTask&) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1923:3
    #37 0x7fcc8217852b in mozilla::ipc::MessageChannel::MessageTask::Run() /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1954:13
    #38 0x7fcc818803ee in mozilla::RunnableTask::Run() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:502:16
    #39 0x7fcc8185e109 in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:805:26
    #40 0x7fcc8185cf78 in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:641:15
    #41 0x7fcc8185d1f3 in mozilla::TaskController::ProcessPendingMTTask(bool) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:425:36
    #42 0x7fcc81883be6 in operator() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:135:37
    #43 0x7fcc81883be6 in mozilla::detail::RunnableFunction<mozilla::TaskController::InitializeInternal()::$_0>::Run() /builds/worker/workspace/obj-build/dist/include/nsThreadUtils.h:534:5
    #44 0x7fcc8186fb5f in nsThread::ProcessNextEvent(bool, bool*) /builds/worker/checkouts/gecko/xpcom/threads/nsThread.cpp:1152:16
    #45 0x7fcc8187679a in NS_ProcessNextEvent(nsIThread*, bool) /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.cpp:548:10
    #46 0x7fcc8217f7d6 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:85:21
    #47 0x7fcc820e7527 in MessageLoop::RunInternal() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:331:10
    #48 0x7fcc820e7442 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:324:3
    #49 0x7fcc820e7442 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:306:3
    #50 0x7fcc85f36cf8 in nsBaseAppShell::Run() /builds/worker/checkouts/gecko/widget/nsBaseAppShell.cpp:137:27
    #51 0x7fcc878dbc03 in XRE_RunAppShell() /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:910:20
    #52 0x7fcc821806ca in mozilla::ipc::MessagePumpForChildProcess::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:235:9
    #53 0x7fcc820e7527 in MessageLoop::RunInternal() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:331:10
    #54 0x7fcc820e7442 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:324:3
    #55 0x7fcc820e7442 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:306:3
    #56 0x7fcc878db81e in XRE_InitChildProcess(int, char**, XREChildData const*) /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:742:34
    #57 0x5566a79acc56 in content_process_main /builds/worker/checkouts/gecko/browser/app/../../ipc/contentproc/plugin-container.cpp:57:28
    #58 0x5566a79acc56 in main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:327:18
    #59 0x7fcc9812a0b2 in __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:308:16

Comment 1

[Bugmon [:jkratzer for issues]]

Bugmon Analysis
Verified bug as reproducible on mozilla-central 20210708154614-ab46ef66acce.
Failed to bisect testcase (Testcase reproduces on start build!):

Start: 37e052bd233427ba430c094622cd7cb44377752c (20200709040358)
End: 536a892dd51f394af6c0638166e8cb7e467ae88c (20210622212907)
BuildFlags: BuildFlags(asan=False, tsan=False, debug=True, fuzzing=True, coverage=False, valgrind=False, no_opt=False, fuzzilli=False)

Comment 2

[Timothy Nikkel (:tnikkel)]

Just investigating this to determine how bad things could go.

Hitting this assert
https://searchfox.org/mozilla-central/rev/3c194fa1d6f339036d2ec9516bd310c6ad612859/layout/painting/nsCSSRenderingGradients.cpp#865
firstStop is -6.2232147213236999e-10, ie very slightly negative.

We fail to enter this if above
https://searchfox.org/mozilla-central/rev/3c194fa1d6f339036d2ec9516bd310c6ad612859/layout/painting/nsCSSRenderingGradients.cpp#824
because stopDelta is 6.3081978356194224e-10 (because laststop is 8.4983114295722473e-12).

This doesn't seem like a problem because lower down
https://searchfox.org/mozilla-central/rev/3c194fa1d6f339036d2ec9516bd310c6ad612859/layout/painting/nsCSSRenderingGradients.cpp#887
we just treat any gradient with such a small stopDelta as de-generate.

->S3.

Comment 3

[Bugmon [:jkratzer for issues]]

Bugmon was unable reproduce this issue.
Removing bugmon keyword as no further action possible. Please review the bug and re-add the keyword for further analysis.

Comment 4

[Jason Kratzer [:jkratzer]]

A change to the Taskcluster build definitions over the weekend caused Bugmon to fail when reproducing issues. This issue has been corrected. Re-enabling bugmon.