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Fix execSequence wildcopy undefined behavior

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execSequence relied on pointer overflow to handle cases where
`sequence.matchLength < 8`.  Instead of passing an `size_t` to
wildcopy, pass a `ptrdiff_t`.
This commit is contained in:
Nick Terrell
2016-12-12 19:01:23 -08:00
parent 4c6ce5a57e
commit 064a143520
9 changed files with 17 additions and 17 deletions
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lib/legacy/zstd_v01.c
+2 -2
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@@ -1354,7 +1354,7 @@ static void ZSTD_copy8(void* dst, const void* src) { memcpy(dst, src, 8); }
#define COPY8(d,s) { ZSTD_copy8(d,s); d+=8; s+=8; }
static void ZSTD_wildcopy(void* dst, const void* src, size_t length)
static void ZSTD_wildcopy(void* dst, const void* src, ptrdiff_t length)
{
const BYTE* ip = (const BYTE*)src;
BYTE* op = (BYTE*)dst;
@@ -1814,7 +1814,7 @@ static size_t ZSTD_execSequence(BYTE* op,
while (op<endMatch) *op++ = *match++;
}
else
ZSTD_wildcopy(op, match, sequence.matchLength-8); /* works even if matchLength < 8 */
ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8); /* works even if matchLength < 8 */
/* restore, in case of overlap */
if (overlapRisk) memcpy(endMatch, saved, qutt);