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From: Matthew DeVore <matvore@google.com>
To: git@vger.kernel.org
Cc: Matthew DeVore <matvore@google.com>,
	jeffhost@microsoft.com, l.s.r@web.de, gitster@pobox.com,
	spearce@spearce.org, jrn@google.com
Subject: [PATCH 2/2] url: do not allow %00 to represent NULL in URLs
Date: Mon,  3 Jun 2019 13:45:26 -0700	[thread overview]
Message-ID: <20190603204526.7723-3-matvore@google.com> (raw)
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


  parent reply	other threads:[~2019-06-03 21:44 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-03 20:45 [PATCH 0/2] Harden url.c URL-decoding logic Matthew DeVore
2019-06-03 20:45 ` [PATCH 1/2] url: do not read past end of buffer Matthew DeVore
2019-06-04  5:00   ` René Scharfe
2019-06-04 17:22     ` Matthew DeVore
2019-06-03 20:45 ` Matthew DeVore [this message]
2019-06-04  1:02   ` [PATCH 2/2] url: do not allow %00 to represent NULL in URLs brian m. carlson
2019-06-04 17:38     ` Matthew DeVore
2019-06-04  5:01   ` René Scharfe
2019-06-04 17:23     ` Matthew DeVore

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