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Refactor dictionary matchfinder index safety check (#4039)

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This commit is contained in:
Federico Maresca
2024-05-29 12:35:24 -04:00
committed by GitHub
parent 0e2ceb2d50
commit 5e9a6c2fe4
5 changed files with 24 additions and 18 deletions
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lib/compress/zstd_opt.c
+2 -2
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@@ -664,13 +664,13 @@ ZSTD_insertBtAndGetAllMatches (
assert(curr >= windowLow);
if ( dictMode == ZSTD_extDict
&& ( ((repOffset-1) /*intentional overflow*/ < curr - windowLow) /* equivalent to `curr > repIndex >= windowLow` */
& (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */)
& (ZSTD_index_overlap_check(dictLimit, repIndex)) )
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch;
}
if (dictMode == ZSTD_dictMatchState
&& ( ((repOffset-1) /*intentional overflow*/ < curr - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `curr > repIndex >= dmsLowLimit` */
& ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */
& (ZSTD_index_overlap_check(dictLimit, repIndex)) )
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch;
} }