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
index 06861bd8bc..694d2f8e40 100644
--- a/wildmatch.c
+++ b/wildmatch.c
@@ -83,12 +83,12 @@ static int dowild(const uchar *p, const uchar *text, unsigned int flags)
continue;
case '*':
if (*++p == '*') {
- const uchar *prev_p = p - 2;
+ const uchar *prev_p = p;
while (*++p == '*') {}
if (!(flags & WM_PATHNAME))
/* without WM_PATHNAME, '*' == '**' */
match_slash = 1;
- else if ((prev_p < pattern || *prev_p == '/') &&
+ else if ((prev_p - pattern < 2 || *(prev_p - 2) == '/') &&
(*p == '\0' || *p == '/' ||
(p[0] == '\\' && p[1] == '/'))) {
/*