CFURL: fix out-of-bounds read when unescaping a trailing percent#39
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CFURL: fix out-of-bounds read when unescaping a trailing percent#39DTW-Thalion wants to merge 1 commit into
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CFURLCreateStringByReplacingPercentEscapesUsingEncoding() read the two hex digits (and the following look-ahead character) after a '%' with "CFStringGetCharacterAtIndex(origString, ++i)" and never checked i against the string length. A string ending in '%' (or '%' followed by a single hex digit) therefore read one or more characters past the end. CFStringGetCharacterAtIndex indexes the backing store directly, so for a string whose buffer is exactly its length (e.g. a no-copy string) this is a genuine out-of-bounds read. Under valgrind, for "abc%": Invalid read of size 1 ... CFURLCreateStringByReplacingPercentEscapesUsingEncoding (CFURL.c:1594) It is reachable from the public CFURLCreateStringByReplacingPercentEscapes. Bound each index against origLen: a '%' not followed by two hex digits is rejected (success = false), and the look-ahead for a further '%' yields 0 at the end of the string so the loop terminates normally. Adds a regression test using a no-copy string ending in '%'.
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CFURLCreateStringByReplacingPercentEscapesUsingEncoding() read the two
hex digits (and the following look-ahead character) after a '%' with
"CFStringGetCharacterAtIndex(origString, ++i)" and never checked i
against the string length. A string ending in '%' (or '%' followed by a
single hex digit) therefore read one or more characters past the end.
CFStringGetCharacterAtIndex indexes the backing store directly, so for a
string whose buffer is exactly its length (e.g. a no-copy string) this is
a genuine out-of-bounds read. Under valgrind, for "abc%":
Invalid read of size 1 ... CFURLCreateStringByReplacingPercentEscapesUsingEncoding (CFURL.c:1594)
It is reachable from the public CFURLCreateStringByReplacingPercentEscapes.
Bound each index against origLen: a '%' not followed by two hex digits is
rejected (success = false), and the look-ahead for a further '%' yields 0
at the end of the string so the loop terminates normally. Adds a
regression test using a no-copy string ending in '%'.