svn commit: r305701 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Allan Jude]

Author: allanjude
Date: Sun Sep 11 17:48:06 2016
New Revision: 305701
URL: https://svnweb.freebsd.org/changeset/base/305701

Log:
  MFV r268120:
    4936 lz4 could theoretically overflow a pointer with a certain input
  
    illumos/illumos-gate at 58d0718061c87e3d647c891ec5281b93c08dba4e
  
  Reviewed by:	delphij
  MFC after:	2 weeks
  Sponsored by:	ScaleEngine Inc.
  Differential Revision:	https://reviews.freebsd.org/D7850

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c	Sun Sep 11 17:44:35 2016	(r305700)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c	Sun Sep 11 17:48:06 2016	(r305701)
@@ -187,21 +187,18 @@ lz4_decompress(void *s_start, void *d_st
     defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
     defined(__LP64__) || defined(_LP64))
 #define	LZ4_ARCH64 1
-/*
- * Illumos: On amd64 we have 20k of stack and 24k on sun4u and sun4v, so we
- * can spend 16k on the algorithm
- */
-/* FreeBSD: Use heap for all platforms for now */
-#define	STACKLIMIT 0
 #else
 #define	LZ4_ARCH64 0
+#endif
+
 /*
- * Illumos: On i386 we only have 12k of stack, so in order to maintain the
- * same COMPRESSIONLEVEL we have to use heap allocation. Performance will
- * suck, but alas, it's ZFS on 32-bit we're talking about, so...
+ * Limits the amount of stack space that the algorithm may consume to hold
+ * the compression lookup table. The value `9' here means we'll never use
+ * more than 2k of stack (see above for a description of COMPRESSIONLEVEL).
+ * If more memory is needed, it is allocated from the heap.
  */
+/* FreeBSD: Use heap for all platforms for now */
 #define	STACKLIMIT 0
-#endif
 
 /*
  * Little Endian or Big Endian?
@@ -870,7 +867,7 @@ real_LZ4_compress(const char *source, ch
 /* Decompression functions */
 
 /*
- * Note: The decoding functionLZ4_uncompress_unknownOutputSize() is safe
+ * Note: The decoding function LZ4_uncompress_unknownOutputSize() is safe
  *	against "buffer overflow" attack type. They will never write nor
  *	read outside of the provided output buffers.
  *	LZ4_uncompress_unknownOutputSize() also insures that it will never
@@ -913,6 +910,9 @@ LZ4_uncompress_unknownOutputSize(const c
 		}
 		/* copy literals */
 		cpy = op + length;
+		/* CORNER-CASE: cpy might overflow. */
+		if (cpy < op)
+			goto _output_error;	/* cpy was overflowed, bail! */
 		if ((cpy > oend - COPYLENGTH) ||
 		    (ip + length > iend - COPYLENGTH)) {
 			if (cpy > oend)