cid#1473321 Division or modulo by float zero

and

cid#1473322 Division or modulo by float zero

where oss-fuzz also found a reproducer as ofz#31370 Divide-by-zero

Change-Id: I0facd2e794384515891dbf040f4fe43530478d3d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/111601
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/emfio/source/reader/mtftools.cxx b/emfio/source/reader/mtftools.cxx
index 29b31438b399..fdb8496f1563 100644
--- a/emfio/source/reader/mtftools.cxx
+++ b/emfio/source/reader/mtftools.cxx
@@ -386,10 +386,13 @@ namespace emfio
             // calculate measured TextLength
             const vcl::Font& rFontCandidate(maCurrentMetaFontAction->GetFont());
             pTempVirtualDevice->SetFont(rFontCandidate);
-            const tools::Long nMeasuredTextLength(pTempVirtualDevice->GetTextWidth(rText));
+            tools::Long nMeasuredTextLength(pTempVirtualDevice->GetTextWidth(rText));
+            // on failure, use original length
+            if (!nMeasuredTextLength)
+                nMeasuredTextLength = nImportedTextLength;
 
             // compare expected and imported TextLengths
-            if (nImportedTextLength != nMeasuredTextLength && nMeasuredTextLength)
+            if (nImportedTextLength != nMeasuredTextLength)
             {
                 const double fFactorText(static_cast<double>(nImportedTextLength) / static_cast<double>(nMeasuredTextLength));
                 const double fFactorTextPercent(fabs(1.0 - fFactorText) * 100.0);
@@ -418,6 +421,9 @@ namespace emfio
                     rFontCandidate2.SetAverageFontWidth(static_cast<tools::Long>(fCorrectedAverageFontWidth));
                     pTempVirtualDevice->SetFont(rFontCandidate2);
                     nCorrectedTextLength = pTempVirtualDevice->GetTextWidth(rText);
+                    // on failure, use original length
+                    if (!nCorrectedTextLength)
+                        nCorrectedTextLength = nImportedTextLength;
                 }
 
                 const double fFactorCorrectedText(static_cast<double>(nImportedTextLength) / static_cast<double>(nCorrectedTextLength));