libsbus_receive: check message length to avoid reading outside it

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 1 insertions, 1 deletions

diff --git a/libsbus.c b/libsbus.c
index 9b8b9ad..4a913ec 100644
--- a/libsbus.c
+++ b/libsbus.c
@@ -69,7 +69,7 @@ libsbus_receive(int fd, int flags, char *buf, union libsbus_packet *packet)
 	if (r < 0)
 		return -1;
 
-	if (!strncmp(buf, "MSG ", 4)) {
+	if (r >= 4 && !strncmp(buf, "MSG ", 4)) {
 		p = memchr(buf, '\0', r);
 		if (!*p++)
 			goto unknown;