Closed Bug 542136 Opened 12 years ago Closed 12 years ago

"ASSERTION: Incorrect aState.mPrevChild before inserting line at end"


(Core :: Layout, defect)

Not set



Tracking Status
blocking1.9.2 --- needed
status1.9.2 --- .2-fixed
blocking1.9.1 --- needed
status1.9.1 --- .9-fixed


(Reporter: jruderman, Assigned: tnikkel)


(Blocks 2 open bugs)


(Keywords: assertion, testcase, verified1.9.2, Whiteboard: [sg:critical?])


(2 files)

Attached file testcase
###!!! ASSERTION: Incorrect aState.mPrevChild before inserting line at end: 'aState.mPrevChild == mFrames.LastChild()', file /Users/jruderman/mozilla-central/layout/generic/nsBlockFrame.cpp, line 2162

bz marked a previous bug with this assertion as security-sensitive (bug 522170), so I'm filing this one as security-sensitive.
Group: core-security
On trunk this assertion shouldn't itself lead to a security problem. On 3.6 and earlier it is likely to cause a messed up frame tree, so a security problem is likely just around the corner.
So I think the problem lies with this bit of code in nsBlockFrame::ReflowInlineFrame

    // If we just ended a first-letter frame or reflowed a placeholder then 
    // don't split the line and don't stop the line reflow...
    if (!(frameReflowStatus & NS_INLINE_BREAK_FIRST_LETTER_COMPLETE) && 
        nsGkAtoms::placeholderFrame != frameType) {
      // Split line after the current frame
      *aLineReflowStatus = LINE_REFLOW_STOP;
      rv = SplitLine(aState, aLineLayout, aLine, aFrame->GetNextSibling(), aLineReflowStatus);
      NS_ENSURE_SUCCESS(rv, rv);

At this point *aLineReflowStatus is already LINE_REFLOW_STOP because the reflow status was break after for the frame we just reflowed, but we don't split the line because of the first letter complete check. And so we stop reflow after 1 of 2 frames on the line and when we get back to nsBlockFrame::ReflowDirtyLines mPrevChild is not the last frame on the line. Adding "|| *aLineReflowStatus == LINE_REFLOW_STOP" to the if condition fixes the asserts for me.
Attached patch patchSplinter Review
Assignee: nobody → tnikkel
Attachment #423615 - Flags: review?(roc)
Closed: 12 years ago
Flags: in-testsuite?
Resolution: --- → FIXED
Target Milestone: --- → mozilla1.9.3a1
After some bake time on trunk this is something that would probably be good to have on the branches.
blocking1.9.1: --- → ?
blocking1.9.2: --- → ?
blocking1.9.1: ? → needed
blocking1.9.2: ? → needed
Whiteboard: [sg:critical?]
Attachment #423615 - Flags: approval1.9.2.2?
Attachment #423615 - Flags: approval1.9.1.9?
Comment on attachment 423615 [details] [diff] [review]

a=beltzner for and
Attachment #423615 - Flags: approval1.9.2.2?
Attachment #423615 - Flags: approval1.9.2.2+
Attachment #423615 - Flags: approval1.9.1.9?
Attachment #423615 - Flags: approval1.9.1.9+
I notice with the testcase post-fix that I'm not seeing the assert above anymore on OS X but I do get:

###!!! ASSERTION: overflow list w/o frames: 'mFrames.NotEmpty()', file /Users/albill/mozilla-192/layout/generic/nsInlineFrame.cpp, line 374

Is this a non-issue?
I don't get that assertion on trunk, I would guess because of bug 533379 which is fixed on trunk but not 1.9.2.
Well, that isn't *this* assertion so I will call this verified1.9.2.
Keywords: verified1.9.2
verified 1.9.2-2 with Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv: Gecko/20100321 Firefox/3.6.2 ID:20100321170417 (debug build) - the testcase didn't caused the assertion from comment #0 - for comment 10 i have made a comment in bug 533379 - maybe that bug need to land on 1.9.2 too
Flags: wanted1.9.0.x-
Group: core-security
Added crashtest
Flags: in-testsuite? → in-testsuite+
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