[PATCH 06/16] fast-import: fix read of uninitialized argv memory

From: Jeff King <peff@peff.net>
Date: Jun 18, 2014, 19:46 UTC
Message-ID: <20140618194615.GF22622@sigill.intra.peff.net>
In-Reply-To: <20140618194117.GA22269@sigill.intra.peff.net>

Fast-import shares code between its command-line parser and the "option" command. To do so, it strips the "--" from any command-line options and passes them to the option parser. However, it does not confirm that the option even begins with "--" before blindly passing "arg + 2".

It does confirm that the option starts with "-", so the only affected case was:

  git fast-import -

which would read uninitialized memory after the argument. We can fix it by using skip_prefix and checking the result. As a bonus, this gets rid of some magic numbers.

Signed-off-by: Jeff King <peff@peff.net>
---
 fast-import.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fast-import.c b/fast-import.c
index 6707a66..b2030cc 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -3342,18 +3342,21 @@ static void parse_argv(void)
 		if (*a != '-' || !strcmp(a, "--"))
 			break;
 
-		if (parse_one_option(a + 2))
+		if (!skip_prefix(a, "--", &a))
+			die("unknown option %s", a);
+
+		if (parse_one_option(a))
 			continue;
 
-		if (parse_one_feature(a + 2, 0))
+		if (parse_one_feature(a, 0))
 			continue;
 
-		if (starts_with(a + 2, "cat-blob-fd=")) {
-			option_cat_blob_fd(a + 2 + strlen("cat-blob-fd="));
+		if (skip_prefix(a, "cat-blob-fd=", &a)) {
+			option_cat_blob_fd(a);
 			continue;
 		}
 
-		die("unknown option %s", a);
+		die("unknown option --%s", a);
 	}
 	if (i != global_argc)
 		usage(fast_import_usage);

-- 
2.0.0.566.gfe3e6b2