New function : LZ4_uncompress : secure version which is safe against buffer overflow attacks

New function : LZ4_uncompress_unknownOutputSize : secure but slower version which also guess the size of data to be decoded
The demo file compression program (main.c) is updated to use these new functions
LZ4_decode is still supported but in deprecated status, due to its vulnerability to malicious buffer overflow scenario


git-svn-id: https://lz4.googlecode.com/svn/trunk@9 650e7d94-2a16-8b24-b05c-7c0b3f6821cd

1 files changed, 39 insertions, 18 deletions

diff --git a/lz4.h b/lz4.h
index b932b39..031e8ee 100644
--- a/lz4.h
+++ b/lz4.h
@@ -34,21 +34,11 @@ extern "C" {
 

 

 //****************************

-// Instructions

-//****************************

-

-// Uncomment next line to ensure that LZ4_Decode will never write in destination buffer more than "decompressedSize" bytes

-// If commented, the decoder may write up to 3 bytes more than decompressedSize, so provide extra room in dest buffer for that

-// Recommendation : keep commented, for improved performance; ensure that destination buffer is at least decompressedSize + 3 Bytes

-// #define SAFEWRITEBUFFER

- 

-

-//****************************

 // Simple Functions

 //****************************

 

-int LZ4_compress (char* source, char* dest, int isize);

-int LZ4_decode   (char* source, char* dest, int isize);

+int LZ4_compress   (char* source, char* dest, int isize);

+int LZ4_uncompress (char* source, char* dest, int osize);

 

 /*

 LZ4_compress :

@@ -57,12 +47,12 @@ LZ4_compress :
 		To avoid any problem, size it to handle worst cases situations (input data not compressible)

 		Worst case size is : "inputsize + 0.4%", with "0.4%" being at least 8 bytes.

 

-LZ4_decode :

-	return : the number of bytes in decoded buffer dest

-	note 1 : isize is the input size, therefore the compressed size

-	note 2 : destination buffer must be already allocated. 

-			The program calling the decoder must know in advance the size of decoded stream to properly allocate the destination buffer

-			Note that, in fast mode, the destination buffer size must be at least "decompressedSize + 3 Bytes"

+LZ4_uncompress :

+	return : the number of bytes read in the source buffer

+			 If the source stream is malformed, the function will stop decoding and return a negative result, indicating the byte position of the faulty instruction

+			 This version never writes beyond dest + osize, and is therefore protected against malicious data packets

+	note 1 : osize is the output size, therefore the original size

+	note 2 : destination buffer must be already allocated

 */

 

 

@@ -70,6 +60,19 @@ LZ4_decode :
 // Advanced Functions

 //****************************

 

+int LZ4_uncompress_unknownOutputSize (char* source, char* dest, int isize, int maxOutputSize);

+

+/*

+LZ4_uncompress :

+	return : the number of bytes decoded in the destination buffer (necessarily <= maxOutputSize)

+			 If the source stream is malformed, the function will stop decoding and return a negative result, indicating the byte position of the faulty instruction

+			 This version never writes beyond dest + osize, and is therefore protected against malicious data packets

+	note 1 : isize is the input size, therefore the compressed size

+	note 2 : destination buffer must be already allocated

+	note 3 : this version is slower by up to 10%, and is therefore not recommended for general use

+*/

+

+

 int LZ4_compressCtx(void** ctx, char* source,  char* dest, int isize);

 

 /*

@@ -85,6 +88,24 @@ LZ4_compressCtx :
 */

 

 

+//****************************

+// Deprecated Functions

+//****************************

+

+int LZ4_decode   (char* source, char* dest, int isize);

+

+/*

+LZ4_decode :

+	return : the number of bytes in decoded buffer dest

+	note 1 : isize is the input size, therefore the compressed size

+	note 2 : destination buffer must be already allocated. 

+			The program calling the decoder must know in advance the size of decoded stream to properly allocate the destination buffer

+			The destination buffer size must be at least "decompressedSize + 3 Bytes"

+			This version is unprotected against malicious data packets designed to create buffer overflow errors.

+			It is therefore deprecated, but still present in this version for compatibility.

+*/

+

+

 #if defined (__cplusplus)

 }

 #endif