[PATCH 1/5] avoid parse_sha1_header() accessing memory out of bound

[Liu Yubao <yubao.liu@gmail.com>]

Signed-off-by: Liu Yubao <yubao.liu@gmail.com>
---
 sha1_file.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/sha1_file.c b/sha1_file.c
index 6c0e251..efe6967 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1245,8 +1245,9 @@ static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size
  * too permissive for what we want to check. So do an anal
  * object header parse by hand.
  */
-static int parse_sha1_header(const char *hdr, unsigned long *sizep)
+static int parse_sha1_header(const char *hdr, unsigned long length, unsigned long *sizep)
 {
+	const char *hdr_end = hdr + length;
 	char type[10];
 	int i;
 	unsigned long size;
@@ -1254,10 +1255,10 @@ static int parse_sha1_header(const char *hdr, unsigned long *sizep)
 	/*
 	 * The type can be at most ten bytes (including the
 	 * terminating '\0' that we add), and is followed by
-	 * a space.
+	 * a space, at least one byte for size, and a '\0'.
 	 */
 	i = 0;
-	for (;;) {
+	while (hdr < hdr_end - 2) {
 		char c = *hdr++;
 		if (c == ' ')
 			break;
@@ -1265,6 +1266,8 @@ static int parse_sha1_header(const char *hdr, unsigned long *sizep)
 		if (i >= sizeof(type))
 			return -1;
 	}
+	if (' ' != *(hdr - 1))
+		return -1;
 	type[i] = 0;
 
 	/*
@@ -1275,7 +1278,7 @@ static int parse_sha1_header(const char *hdr, unsigned long *sizep)
 	if (size > 9)
 		return -1;
 	if (size) {
-		for (;;) {
+		while (hdr < hdr_end - 1) {
 			unsigned long c = *hdr - '0';
 			if (c > 9)
 				break;
@@ -1298,7 +1301,7 @@ static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type
 	char hdr[8192];
 
 	ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
-	if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
+	if (ret < Z_OK || (*type = parse_sha1_header(hdr, stream.total_out, size)) < 0)
 		return NULL;
 
 	return unpack_sha1_rest(&stream, hdr, *size, sha1);
@@ -1982,7 +1985,7 @@ static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *size
 	if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 		status = error("unable to unpack %s header",
 			       sha1_to_hex(sha1));
-	else if ((status = parse_sha1_header(hdr, &size)) < 0)
+	else if ((status = parse_sha1_header(hdr, stream.total_out, &size)) < 0)
 		status = error("unable to parse %s header", sha1_to_hex(sha1));
 	else if (sizep)
 		*sizep = size;
-- 
1.6.1.rc1.5.gde86c