50 lines
1.7 KiB
Diff
50 lines
1.7 KiB
Diff
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Mitigate Spectre by reducing the resolution of performance.now() to 20
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microseconds. Based on:
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https://hg.mozilla.org/releases/mozilla-release/rev/afa87f9be3a8
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For more details, see:
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https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/
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This patch was modified to apply cleanly to GNU IceCat.
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# HG changeset patch
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# User Tom Ritter <tom@mozilla.com>
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# Date 1514660820 21600
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# Node ID afa87f9be3a8852da3a30f286b15ae599c7874f6
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# Parent 6caa457ebedc915b43dc1d054b8fe22e82ca7447
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Bug 1427870 - Change resolution of .now() to 20us. r=bkelly, a=lizzard
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The comment about workers was introduced in Bug 1186489 but became obsolete some time after that
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(definitely by Bug 1278838)
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diff --git a/dom/performance/Performance.cpp b/dom/performance/Performance.cpp
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--- a/dom/performance/Performance.cpp
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+++ b/dom/performance/Performance.cpp
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@@ -234,20 +234,19 @@ Performance::ClearResourceTimings()
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{
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MOZ_ASSERT(NS_IsMainThread());
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mResourceEntries.Clear();
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}
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DOMHighResTimeStamp
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Performance::RoundTime(double aTime) const
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{
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- // Round down to the nearest 5us, because if the timer is too accurate people
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- // can do nasty timing attacks with it. See similar code in the worker
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- // Performance implementation.
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- const double maxResolutionMs = 0.005;
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+ // Round down to the nearest 20us, because if the timer is too accurate people
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+ // can do nasty timing attacks with it.
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+ const double maxResolutionMs = 0.020;
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return floor(aTime / maxResolutionMs) * maxResolutionMs;
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}
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void
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Performance::Mark(const nsAString& aName, ErrorResult& aRv)
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{
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// Don't add the entry if the buffer is full. XXX should be removed by bug 1159003.
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