From: Jeff King <peff@peff.net>
Date: Sun, 13 May 2018 16:09:42 +0000 (-0400)
Subject: is_ntfs_dotgit: use a size_t for traversing string
X-Git-Tag: v2.13.7~1^2~8
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=11a9f4d807a0d71dc6eff51bb87baf4ca2cccf1d;p=thirdparty%2Fgit.git

is_ntfs_dotgit: use a size_t for traversing string

We walk through the "name" string using an int, which can
wrap to a negative value and cause us to read random memory
before our array (e.g., by creating a tree with a name >2GB,
since "int" is still 32 bits even on most 64-bit platforms).
Worse, this is easy to trigger during the fsck_tree() check,
which is supposed to be protecting us from malicious
garbage.

Note one bit of trickiness in the existing code: we
sometimes assign -1 to "len" at the end of the loop, and
then rely on the "len++" in the for-loop's increment to take
it back to 0. This is still legal with a size_t, since
assigning -1 will turn into SIZE_MAX, which then wraps
around to 0 on increment.

Signed-off-by: Jeff King <peff@peff.net>
---

diff --git a/path.c b/path.c
index 0349a0ab7b..9018aa0ac0 100644
--- a/path.c
+++ b/path.c
@@ -1224,7 +1224,7 @@ static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 
 int is_ntfs_dotgit(const char *name)
 {
-	int len;
+	size_t len;
 
 	for (len = 0; ; len++)
 		if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {