Merge pull request #6197 from Rob--W/issue6108

Improve robustness of stream parser (invalid length)

src/core/parser.js

@@ -53,6 +53,16 @@ var Parser = (function ParserClosure() {
         this.buf2 = this.lexer.getObj();
       }
     },
+    tryShift: function Parser_tryShift() {
+      try {
+        this.shift();
+        return true;
+      } catch (e) {
+        // Upon failure, the caller should reset this.lexer.pos to a known good
+        // state and call this.shift() twice to reset the buffers.
+        return false;
+      }
+    },
     getObj: function Parser_getObj(cipherTransform) {
       var buf1 = this.buf1;
       this.shift();
@@ -426,9 +436,10 @@ var Parser = (function ParserClosure() {
       stream.pos = pos + length;
       lexer.nextChar();
 
-      this.shift(); // '>>'
-      this.shift(); // 'stream'
-      if (!isCmd(this.buf1, 'endstream')) {
+      // Shift '>>' and check whether the new object marks the end of the stream
+      if (this.tryShift() && isCmd(this.buf2, 'endstream')) {
+        this.shift(); // 'stream'
+      } else {
         // bad stream length, scanning for endstream
         stream.pos = pos;
         var SCAN_BLOCK_SIZE = 2048;

test/pdfs/.gitignore

@@ -146,3 +146,4 @@
 !issue6068.pdf
 !issue6081.pdf
 !issue6069.pdf
+!issue6108.pdf

test/pdfs/issue6108.pdf

@@ -0,0 +1,28 @@
+%PDF-1.0
+1 0 obj
+<</Type/Catalog/Pages 2 0 R>>
+endobj
+2 0 obj
+<</Type/Pages/Count 1/Kids[3 0 R]/MediaBox [0 0 400 50]>>
+endobj
+3 0 obj
+<</Type/Page/Parent 2 0 R/Resources<</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Arial>>>>>>/Contents 4 0 R>>
+endobj
+4 0 obj
+<</Length 9/Filter/ASCIIHexDecode>>
+stream
+42542F4631203132205466203230203230205464202841534349494865784465636F64652066696C7465722C20736D616C6C204C656E6774682C2073697A652064696666206973206D6F7265207468616E203133352062797465732920546A204554>
+endstream
+endobj
+xref
+0 5
+0000000000 65535 f 
+0000000009 00000 n 
+0000000054 00000 n 
+0000000127 00000 n 
+0000000254 00000 n 
+trailer
+<</Root 1 0 R/Size 5>>
+startxref
+519
+%%EOF

test/test_manifest.json

@@ -2284,5 +2284,11 @@
        "md5": "d0ad8871f4116bca8e39513ffa8b7d8e",
        "rounds": 1,
        "type": "load"
+    },
+    {  "id": "issue6108",
+       "file": "pdfs/issue6108.pdf",
+       "md5": "8961cb55149495989a80bf0487e0f076",
+       "rounds": 1,
+       "type": "load"
     }
 ]