[poppler] poppler/JBIG2Stream.cc

[Albert Astals Cid]

 poppler/JBIG2Stream.cc |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

New commits:
commit e950107006a3b1889646d3705323c1b3d41eaa49
Author: David Benjamin <davidben at mit.edu>
Date:   Wed Sep 9 01:19:38 2009 +0200

    Fix infinite loop in JBIG2Decoder
    
    Bug 23025
    Also fixes problems in bug-poppler6881-2.pdf and bug-poppler6500.pdf

diff --git a/poppler/JBIG2Stream.cc b/poppler/JBIG2Stream.cc
index fec0e2d..97994bd 100644
--- a/poppler/JBIG2Stream.cc
+++ b/poppler/JBIG2Stream.cc
@@ -1587,12 +1587,15 @@ GBool JBIG2Stream::readSymbolDictSeg(Guint segNum, Guint length,
     goto eofError;
   }
 
-  // compute symbol code length
+  // compute symbol code length, per 6.5.8.2.3
+  //  symCodeLen = ceil( log2( numInputSyms + numNewSyms ) )
   symCodeLen = 1;
-  i = (numInputSyms + numNewSyms) >> 1;
-  while (i) {
-    ++symCodeLen;
-    i >>= 1;
+  if (likely(numInputSyms + numNewSyms > 0)) { // don't fail too badly if the sum is 0
+    i = (numInputSyms + numNewSyms - 1) >> 1;
+    while (i) {
+      ++symCodeLen;
+      i >>= 1;
+    }
   }
 
   // get the input symbol bitmaps