CVE-2021-36978 安全更新：当某个下游写操作失败时，QPDF中存在基于堆的缓冲区溢出漏洞

debian/changelog

@@ -1,3 +1,9 @@
+qpdf (9.1.1-ok3) yangtze; urgency=medium
+
+  * omelette-guo CVE-2021-36978 安全更新：当某个下游写操作失败时，QPDF中存在基于堆的缓冲区溢出漏洞
+
+ -- lichaoheng <o_o@bupt.edu.cn>  Tue, 14 Mar 2023 11:06:54 +0800
+
 qpdf (9.1.1-ok2) yangtze; urgency=medium
 
   * Update version.

libqpdf/Pl_AES_PDF.cc

@@ -238,6 +238,6 @@ Pl_AES_PDF::flush(bool strip_padding)
 	    }
 	}
     }
-    getNext()->write(this->outbuf, bytes);
     this->offset = 0;
+    getNext()->write(this->outbuf, bytes);
 }

libqpdf/Pl_ASCII85Decoder.cc

@@ -119,10 +119,13 @@ Pl_ASCII85Decoder::flush()
 
     QTC::TC("libtests", "Pl_ASCII85Decoder partial flush",
 	    (this->pos == 5) ? 0 : 1);
-    getNext()->write(outbuf, this->pos - 1);
-
+    // Reset before calling getNext()->write in case that throws an
+    // exception.
+    auto t = this->pos - 1;
     this->pos = 0;
     memset(this->inbuf, 117, 5);
+
+    getNext()->write(outbuf, t);
 }
 
 void

libqpdf/Pl_ASCIIHexDecoder.cc

@@ -97,12 +97,14 @@ Pl_ASCIIHexDecoder::flush()
 
     QTC::TC("libtests", "Pl_ASCIIHexDecoder partial flush",
 	    (this->pos == 2) ? 0 : 1);
-    getNext()->write(&ch, 1);
-
+    // Reset before calling getNext()->write in case that throws an
+    // exception.
     this->pos = 0;
     this->inbuf[0] = '0';
     this->inbuf[1] = '0';
     this->inbuf[2] = '\0';
+
+    getNext()->write(&ch, 1);
 }
 
 void

libqpdf/Pl_Count.cc

@@ -27,8 +27,8 @@ Pl_Count::write(unsigned char* buf, size_t len)
     if (len)
     {
 	this->m->count += QIntC::to_offset(len);
-	getNext()->write(buf, len);
 	this->m->last_char = buf[len - 1];
+	getNext()->write(buf, len);
     }
 }