wildmatch: avoid undefined behavior
The code changed in this commit is designed to check if the pattern starts with "**/" or contains "/**/" (see 3a078dec33 (wildmatch: fix "**" special case, 2013-01-01)). Unfortunately when the pattern begins with "**/" `prev_p = p - 2` is evaluated when `p` points to the second "*" and so the subtraction is undefined according to section 6.5.6 of the C standard because the result does not point within the same object as `p`. Fix this by avoiding the subtraction unless it is well defined. Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Phillip Wood committed
Mar 20, 2023 at 16:10 UTC
81b26f8f2891f1a63d5dbf7c2d4209b8325062b6
1 file changed
+2
-2
wildmatch.c
+2
-2
@@ -83,12 +83,12 @@ static int dowild(const uchar *p, const uchar *text, unsigned int flags)
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continue;
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case '*':
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if (*++p == '*') {
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- const uchar *prev_p = p - 2;
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+ const uchar *prev_p = p;
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while (*++p == '*') {}
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if (!(flags & WM_PATHNAME))
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/* without WM_PATHNAME, '*' == '**' */
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match_slash = 1;
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- else if ((prev_p < pattern || *prev_p == '/') &&
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+ else if ((prev_p - pattern < 2 || *(prev_p - 2) == '/') &&
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(*p == '\0' || *p == '/' ||
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(p[0] == '\\' && p[1] == '/'))) {
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/*