[PATCH 2/2] url: do not allow %00 to represent NULL in URLs

From: Matthew DeVore <matvore@google.com>
Date: Jun 3, 2019, 20:45 UTC
Message-ID: <20190603204526.7723-3-matvore@google.com>
In-Reply-To: <20190603204526.7723-1-matvore@google.com>

There is no reason to allow %00 to terminate a string, so do not allow it. Otherwise, we end up returning arbitrary content in the string (that which is after the %00) which is effectively hidden from callers and can escape sanity checks and validation, and possible be used in tandem with a security vulnerability to introduce a payload.

Signed-off-by: Matthew DeVore <matvore@google.com>
---
 url.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/url.c b/url.c
index c0bb4e23c3..cf791cb139 100644
--- a/url.c
+++ b/url.c
@@ -41,21 +41,21 @@ static char *url_decode_internal(const char **query, int len,
 		if (!c)
 			break;
 		if (stop_at && strchr(stop_at, c)) {
 			q++;
 			len--;
 			break;
 		}
 
 		if (c == '%' && len >= 3) {
 			int val = hex2chr(q + 1);
-			if (0 <= val) {
+			if (0 < val) {
 				strbuf_addch(out, val);
 				q += 3;
 				len -= 3;
 				continue;
 			}
 		}
 
 		if (decode_plus && c == '+')
 			strbuf_addch(out, ' ');
 		else

-- 
2.17.1