dlm: missing length check in check_config()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index 3f9b96fd26e8..a312f1d97f8b 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -85,6 +85,7 @@ static void make_config(struct dlm_ls *ls, struct rcom_config *rf)
 static int check_config(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid)
 {
         struct rcom_config *rf = (struct rcom_config *) rc->rc_buf;
+        size_t conf_size = sizeof(struct dlm_rcom) + sizeof(struct rcom_config);
 
         if ((rc->rc_header.h_version & 0xFFFF0000) != DLM_HEADER_MAJOR) {
                 log_error(ls, "version mismatch: %x nodeid %d: %x",
@@ -93,6 +94,12 @@ static int check_config(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid)
                 return -EPROTO;
         }
 
+        if (rc->rc_header.h_length < conf_size) {
+                log_error(ls, "config too short: %d nodeid %d",
+                          rc->rc_header.h_length, nodeid);
+                return -EPROTO;
+        }
+
         if (le32_to_cpu(rf->rf_lvblen) != ls->ls_lvblen ||
             le32_to_cpu(rf->rf_lsflags) != ls->ls_exflags) {
                 log_error(ls, "config mismatch: %d,%x nodeid %d: %d,%x",