CFArray: fix off-by-one in CFArrayGetLastIndexOfValue#46
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CFArrayGetLastIndexOfValue() began its backward scan at range.location + range.length, i.e. one past the last index in the range (the last valid index is range.location + range.length - 1). The first comparison therefore read one element beyond the range; when the range covers a full array whose count equals its capacity this is an out-of-bounds read (AddressSanitizer: heap-buffer-overflow READ in CFArrayGetValueAtIndex, from CFArrayGetLastIndexOfValue). The forward counterpart, CFArrayGetFirstIndexOfValue(), already stops correctly at range.location + range.length. Start the scan at range.location + range.length - 1. An empty range now also skips the loop instead of reading at range.location. Adds a regression test.
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CFArrayGetLastIndexOfValue() began its backward scan at
range.location + range.length, i.e. one past the last index in the range
(the last valid index is range.location + range.length - 1). The first
comparison therefore read one element beyond the range; when the range
covers a full array whose count equals its capacity this is an
out-of-bounds read (AddressSanitizer: heap-buffer-overflow READ in
CFArrayGetValueAtIndex, from CFArrayGetLastIndexOfValue). The forward
counterpart, CFArrayGetFirstIndexOfValue(), already stops correctly at
range.location + range.length.
Start the scan at range.location + range.length - 1. An empty range now
also skips the loop instead of reading at range.location. Adds a
regression test.