698335 - "ASSERTION: Invalid offset" with bidi, -moz-column, :first-letter

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Jesse Ruderman]

Attachment: testcase (hangs Firefox)

###!!! ASSERTION: Invalid offset: 'aOffset <= mSkipChars->mCharCount', file gfx/thebes/gfxSkipChars.cpp, line 92

###!!! ASSERTION: Text run does not map enough text for our reflow: 'gfxSkipCharsIterator(iter).ConvertOriginalToSkipped(offset + length) <= mTextRun->GetLength()', file layout/generic/nsTextFrameThebes.cpp, line 7109

###!!! ASSERTION: Invalid offset: 'aOffset <= mSkipChars->mCharCount', file gfx/thebes/gfxSkipChars.cpp, line 92

###!!! ASSERTION: unconstrained height on totally empty line: 'NS_UNCONSTRAINEDSIZE != aFloatAvailableSpace.mRect.height', file layout/generic/nsBlockFrame.cpp, line 3686

###!!! ASSERTION: redo line on totally empty line with non-empty band...: 'aFloatAvailableSpace.mHasFloats', file layout/generic/nsBlockFrame.cpp, line 3691

Comment 1

[Jesse Ruderman]

Attachment: stack traces

Comment 2

[Daniel Veditz [:dveditz]]

Is this exploitable or just a DoS/hang? would more/fewer/different characters change the symptoms?

Comment 3

[Tanvi Vyas[:tanvi]]

smontagu - any update here?

Comment 4

[Simon Montagu :smontagu]

Attachment: Patch

This is apparently regression from making a preformatted newline a new bidi paragraph: we need to test whether there are any fluid continuations even beyond the current paragraph, but children of the same block element and convert them to non-fluid.

Comment 5

[Simon Montagu :smontagu]

https://hg.mozilla.org/integration/mozilla-inbound/rev/60add44419ef

Comment 6

[Simon Montagu :smontagu]

https://hg.mozilla.org/mozilla-central/rev/60add44419ef

Comment 7

[Daniel Veditz [:dveditz]]

Do we need to land this on Aurora as a security bug or did it turn out benign and we can unhide the bug? If it really is a potentially sg:critical bug we maybe shouldn't have called it out in the Platform meeting, especially with a checked-in crashtest.

Comment 8

[Simon Montagu :smontagu]

Regression window is http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a666b4f809f0&tochange=953f9620f395, which is not what I expected: possibly bug 578977?

Comment 9

[Simon Montagu :smontagu]

Comment on attachment 588753 [details] [diff] [review]
Patch

This doesn't seem exploitable to me, but since we have a simple patch let's fix it on aurora and beta.

[Approval Request Comment]
Regression caused by (bug #): 578977(? see comment 8)
User impact if declined: hangs and possible crashes
Testing completed (on m-c, etc.): baked 6 days on m-c, has crashtest.
Risk to taking this patch (and alternatives if risky): minimal.

Comment 10

[Mats Palmgren (inactive)]

(In reply to Simon Montagu from comment #8)
> possibly bug 578977?

Confirmed by reverting bug 578977 in an Aurora debug build on Linux.
Bug 578977 did change some things that affects next-in-flows of first-letter
frames, so it makes sense.

Comment 11

[Curtis Koenig [:curtisk-use curtis.koenig+bzATgmail.com]]]

given comment 9 I think we can hold off on this given timing for 10. But we should be able to land this on Aurora, we can cover that in the next triage/channel mtg.

Comment 12

[Alex Keybl [:akeybl]]

Comment on attachment 588753 [details] [diff] [review]
Patch

[Triage Comment]
We don't have any evidence that this is exploitable or causing significant user pain - let's let this ride the train.

Comment 13

[Virgil Dicu [:virgil] [QA]]

Verified using linux debug build on Ubuntu 11.10 with beta debug build (18.4.2012)- no hang/assertion when loading the test case from comment 0.