From e50ed1fa3ac5857b6be914ec818a71c914789d4f Mon Sep 17 00:00:00 2001 From: Stella Lau Date: Tue, 22 Aug 2017 11:55:42 -0700 Subject: [PATCH] Fix undefined behavior when srcSize==1 --- lib/common/bitstream.h | 33 ++++++++++++++++++--------------- lib/common/zstd_internal.h | 31 +++++++++++++++++-------------- lib/compress/zstd_compress.c | 3 ++- 3 files changed, 37 insertions(+), 30 deletions(-) diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h index 06121f21c..c6f001248 100644 --- a/lib/common/bitstream.h +++ b/lib/common/bitstream.h @@ -169,25 +169,28 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits); ****************************************************************/ MEM_STATIC unsigned BIT_highbit32 (register U32 val) { + assert(val != 0); + { # if defined(_MSC_VER) /* Visual */ - unsigned long r=0; - _BitScanReverse ( &r, val ); - return (unsigned) r; + unsigned long r=0; + _BitScanReverse ( &r, val ); + return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return 31 - __builtin_clz (val); # else /* Software version */ - static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, - 11, 14, 16, 18, 22, 25, 3, 30, - 8, 12, 20, 28, 15, 17, 24, 7, - 19, 27, 23, 6, 26, 5, 4, 31 }; - U32 v = val; - v |= v >> 1; - v |= v >> 2; - v |= v >> 4; - v |= v >> 8; - v |= v >> 16; - return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27]; + static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, + 11, 14, 16, 18, 22, 25, 3, 30, + 8, 12, 20, 28, 15, 17, 24, 7, + 19, 27, 23, 6, 26, 5, 4, 31 }; + U32 v = val; + v |= v >> 1; + v |= v >> 2; + v |= v >> 4; + v |= v >> 8; + v |= v >> 16; + return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27]; # endif + } } /*===== Local Constants =====*/ diff --git a/lib/common/zstd_internal.h b/lib/common/zstd_internal.h index 261052860..ac1f39896 100644 --- a/lib/common/zstd_internal.h +++ b/lib/common/zstd_internal.h @@ -268,24 +268,27 @@ void ZSTD_free(void* ptr, ZSTD_customMem customMem); MEM_STATIC U32 ZSTD_highbit32(U32 val) { + assert(val != 0); + { # if defined(_MSC_VER) /* Visual */ - unsigned long r=0; - _BitScanReverse(&r, val); - return (unsigned)r; + unsigned long r=0; + _BitScanReverse(&r, val); + return (unsigned)r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */ - return 31 - __builtin_clz(val); + return 31 - __builtin_clz(val); # else /* Software version */ - static const int DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; - U32 v = val; - int r; - v |= v >> 1; - v |= v >> 2; - v |= v >> 4; - v |= v >> 8; - v |= v >> 16; - r = DeBruijnClz[(U32)(v * 0x07C4ACDDU) >> 27]; - return r; + static const int DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; + U32 v = val; + int r; + v |= v >> 1; + v |= v >> 2; + v |= v >> 4; + v |= v >> 8; + v |= v >> 16; + r = DeBruijnClz[(U32)(v * 0x07C4ACDDU) >> 27]; + return r; # endif + } } diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index 0322c03eb..31e941596 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -497,7 +497,8 @@ ZSTD_compressionParameters ZSTD_adjustCParams_internal(ZSTD_compressionParameter { U32 const minSrcSize = (srcSize==0) ? 500 : 0; U64 const rSize = srcSize + dictSize + minSrcSize; if (rSize < ((U64)1< srcLog) cPar.windowLog = srcLog; } } if (cPar.hashLog > cPar.windowLog) cPar.hashLog = cPar.windowLog; -- 2.47.2