From e68c7d38780ada518e6c43a09a2d92421ea8111b Mon Sep 17 00:00:00 2001 From: Alexander Gallego Date: Wed, 8 Jul 2020 08:21:45 -0700 Subject: avoid computing 0 offsets from null pointers Similar work in the kernel: https://patchwork.kernel.org/patch/11351499/ UBsan (+clang-10) complains about doing pointer arithmetic (adding 0) to a nullpointer. This patch is tested with clang-10+ubsan --- lib/lz4.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/lz4.c b/lib/lz4.c index 82ab490..2f7880a 100644 --- a/lib/lz4.c +++ b/lib/lz4.c @@ -819,7 +819,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic( int const maybe_extMem = (dictDirective == usingExtDict) || (dictDirective == usingDictCtx); U32 const prefixIdxLimit = startIndex - dictSize; /* used when dictDirective == dictSmall */ - const BYTE* const dictEnd = dictionary + dictSize; + const BYTE* const dictEnd = dictionary ? dictionary + dictSize : dictionary; const BYTE* anchor = (const BYTE*) source; const BYTE* const iend = ip + inputSize; const BYTE* const mflimitPlusOne = iend - MFLIMIT + 1; @@ -827,7 +827,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic( /* the dictCtx currentOffset is indexed on the start of the dictionary, * while a dictionary in the current context precedes the currentOffset */ - const BYTE* dictBase = (dictDirective == usingDictCtx) ? + const BYTE* dictBase = !dictionary ? NULL : (dictDirective == usingDictCtx) ? dictionary + dictSize - dictCtx->currentOffset : dictionary + dictSize - startIndex; -- cgit v0.12