[PATCH 2/3] wildmatch: avoid undefined behavior
- From
- Phillip Wood <phillip.wood123@gmail.com>
- Date
- Mar 20, 2023, 16:10 UTC
- Message-ID
- <c6f2d44622f10cfee3c48a7d13b3de9607d1061d.1679328580.git.phillip.wood@dunelm.org.uk>
- In-Reply-To
- <cover.1679328580.git.phillip.wood@dunelm.org.uk>
From: Phillip Wood <phillip.wood@dunelm.org.uk>
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> --- wildmatch.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/wildmatch.c b/wildmatch.c 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] == '/'))) { /*
-- 2.39.2