crashtesting: UaF on layout of ooo98566-1.odt

in:
sw/source/core/text/itrform2.cxx:2643 SwTextFormatter::NewFlyCntPortion
at: pFly = static_cast<SwTextFlyCnt*>(pHint)->GetFlyFrame(pFrame)

(gdb) print m_pCurr
$2 = (SwLineLayout *) 0x55ea220a0020

after calling GetFlyFrame m_pCurr is unchanged and we will call
m_pCurr->MaxAscentDescent
on it.

But m_pCurr is deleted during GetFlyFrame by...

 #18 0x00007f98c5cd337f in SwLineLayout::~SwLineLayout() (this=this@entry=0x55ea220a0020, __in_chrg=<optimized out>)
     at source/libo-core/sw/source/core/text/portxt.hxx:26
 #19 0x00007f98c5cd347a in SwParaPortion::~SwParaPortion() (this=0x55ea220a0020, __in_chrg=<optimized out>)
     at source/libo-core/sw/source/core/text/porlay.cxx:2491
 #20 0x00007f98c5cd3485 in SwParaPortion::~SwParaPortion() (this=0x55ea220a0020, __in_chrg=<optimized out>)
     at source/libo-core/sw/source/core/text/porlay.cxx:2491
 #21 0x00007f98c5d05e70 in std::default_delete<SwParaPortion>::operator()(SwParaPortion*) const (__ptr=<optimized out>, this=<optimized out>)
     at /usr/include/c++/8/bits/unique_ptr.h:75
 #22 0x00007f98c5d05e70 in std::unique_ptr<SwParaPortion, std::default_delete<SwParaPortion> >::reset(SwParaPortion*)
     (__p=<optimized out>, this=<optimized out>) at /usr/include/c++/8/bits/unique_ptr.h:382
 #23 0x00007f98c5d05e70 in SwTextLine::SetPara(SwParaPortion*, bool) (bDelete=true, pNew=0x0, this=<optimized out>)
     at source/libo-core/sw/source/core/text/txtcache.hxx:45
 #24 0x00007f98c5d05e70 in SwTextFrame::ClearPara() (this=this@entry=0x55ea21302b60) at source/libo-core/sw/source/core/text/txtcache.cxx:113
 #25 0x00007f98c5d1be89 in SwTextFrame::Init() (this=this@entry=0x55ea21302b60) at source/libo-core/sw/source/core/text/txtfrm.cxx:757
 #26 0x00007f98c5d2630c in SwTextFrame::Prepare(PrepareHint, void const*, bool)
     (this=0x55ea21302b60, ePrep=PrepareHint::FlyFrameArrive, pVoid=<optimized out>, bNotify=<optimized out>)
     at source/libo-core/sw/source/core/text/txtfrm.cxx:3086
 #27 0x00007f98c5b1edb8 in SwFlyInContentFrame::NotifyBackground(SwPageFrame*, SwRect const&, PrepareHint)
     (this=<optimized out>, rRect=..., eHint=<optimized out>) at source/libo-core/sw/inc/anchoredobject.hxx:205
 #28 0x00007f98c5b261a6 in Notify(SwFlyFrame*, SwPageFrame*, SwRect const&, SwRect const*)
     (pFly=pFly@entry=0x55ea21a18d60, pOld=0x0, rOld=SwRect = {...}, pOldPrt=pOldPrt@entry=0x7ffeb50390f8)
     at source/libo-core/sw/source/core/inc/frame.hxx:1177
 #29 0x00007f98c5b2ceca in SwFlyNotify::~SwFlyNotify() (this=0x7ffeb50390d0, __in_chrg=<optimized out>)
     at source/libo-core/sw/source/core/layout/frmtool.cxx:648
 #30 0x00007f98c5b1fa25 in SwFlyInContentFrame::MakeAll(OutputDevice*) (this=0x55ea21a18d60)
     at source/libo-core/sw/source/core/inc/frmtool.hxx:419
 #31 0x00007f98c5aec3a9 in SwFrame::PrepareMake(OutputDevice*) (this=0x55ea21a18d60, pRenderContext=0x55ea212bc4c0)
     at source/libo-core/sw/source/core/layout/calcmove.cxx:375
 #32 0x00007f98c5b17ad2 in SwFlyFrame::Calc(OutputDevice*) const (this=<optimized out>, pRenderContext=<optimized out>)
     at source/libo-core/sw/source/core/layout/fly.cxx:2890
 #33 0x00007f98c5b636c5 in SwObjectFormatter::FormatLayout_(SwLayoutFrame&) (this=this@entry=0x55ea2244d150, _rLayoutFrame=...)
     at source/libo-core/include/rtl/ref.hxx:206
 #34 0x00007f98c5b6413e in SwObjectFormatter::FormatObj_(SwAnchoredObject&) (this=this@entry=0x55ea2244d150, _rAnchoredObj=...)
     at source/libo-core/sw/source/core/layout/objectformatter.cxx:296
 #35 0x00007f98c5b6705b in SwObjectFormatterTextFrame::DoFormatObj(SwAnchoredObject&, bool)
     (this=0x55ea2244d150, _rAnchoredObj=..., _bCheckForMovedFwd=<optimized out>)
     at source/libo-core/sw/source/core/layout/objectformattertxtfrm.cxx:136
 #36 0x00007f98c5b6359f in SwObjectFormatter::FormatObj(SwAnchoredObject&, SwFrame*, SwPageFrame const*)
     (_rAnchoredObj=..., _pAnchorFrame=<optimized out>, _pPageFrame=<optimized out>)
     at source/libo-core/sw/source/core/layout/objectformatter.cxx:190
 #37 0x00007f98c5d717aa in SwTextFlyCnt::GetFlyFrame_(SwFrame const*) (this=this@entry=0x55ea214d8810, pCurrFrame=pCurrFrame@entry=0x55ea21302b60)
     at source/libo-core/sw/source/core/inc/frame.hxx:1177
 #38 0x00007f98c5cb511b in SwTextFlyCnt::GetFlyFrame(SwFrame const*) (pCurrFrame=0x55ea21302b60, this=0x55ea214d8810)
     at source/libo-core/sw/inc/txtflcnt.hxx:48
 #39 0x00007f98c5cb511b in SwTextFormatter::NewFlyCntPortion(SwTextFormatInfo&, SwTextAttr*) const
     (this=this@entry=0x7ffeb503a6b0, rInf=..., pHint=0x55ea214d8810) at source/libo-core/sw/source/core/text/itrform2.cxx:2643

(gdb) print this
(SwLinePortion * const) 0x55ea220a0020

The SwTextFrame of SwTextFrame::ClearPara is the same pFrame/m_pFrame at SwTextFormatter::NewFlyCntPortion

ClearPara is not called if the SwTextFrame is "Locked", so try using that to protect GetFlyFrame

Change-Id: Ia9dcb1f345f6953d995f2acf1ec23492d1680364
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/118784
Tested-by: Jenkins
Tested-by: Caolán McNamara <[email protected]>
Reviewed-by: Caolán McNamara <[email protected]>

sw/source/core/text/itrform2.cxx

@@ -2627,7 +2627,11 @@ SwFlyCntPortion *SwTextFormatter::NewFlyCntPortion( SwTextFormatInfo &rInf,
     SwFlyInContentFrame *pFly;
     SwFrameFormat* pFrameFormat = static_cast<SwTextFlyCnt*>(pHint)->GetFlyCnt().GetFrameFormat();
     if( RES_FLYFRMFMT == pFrameFormat->Which() )
+    {
+        // set Lock pFrame to avoid m_pCurr getting deleted
+        TextFrameLockGuard aGuard(m_pFrame);
         pFly = static_cast<SwTextFlyCnt*>(pHint)->GetFlyFrame(pFrame);
+    }
     else
         pFly = nullptr;
     // aBase is the document-global position, from which the new extra portion is placed