dlm: receive_rcom_lock_args() overflow check

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

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 6c605fc10613..0593dd81d46d 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -4271,7 +4271,6 @@ static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
                                   struct dlm_rsb *r, struct dlm_rcom *rc)
 {
         struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
-        int lvblen;
 
         lkb->lkb_nodeid = rc->rc_header.h_nodeid;
         lkb->lkb_ownpid = le32_to_cpu(rl->rl_ownpid);
@@ -4288,11 +4287,13 @@ static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
         lkb->lkb_astaddr = (void *) (long) (rl->rl_asts & AST_COMP);
 
         if (lkb->lkb_exflags & DLM_LKF_VALBLK) {
+                int lvblen = rc->rc_header.h_length - sizeof(struct dlm_rcom) -
+                         sizeof(struct rcom_lock);
+                if (lvblen > ls->ls_lvblen)
+                        return -EINVAL;
                 lkb->lkb_lvbptr = dlm_allocate_lvb(ls);
                 if (!lkb->lkb_lvbptr)
                         return -ENOMEM;
-                lvblen = rc->rc_header.h_length - sizeof(struct dlm_rcom) -
-                         sizeof(struct rcom_lock);
                 memcpy(lkb->lkb_lvbptr, rl->rl_lvb, lvblen);
         }