nfsd: memory corruption in nfsd4_lock()

New struct nfsd4_blocked_lock allocated in find_or_allocate_block()
does not initialized nbl_list and nbl_lru.
If conflock allocation fails rollback can call list_del_init()
access uninitialized fields and corrupt memory.

v2: just initialize nbl_list and nbl_lru right after nbl allocation.

Fixes: 76d348fadff5 ("nfsd: have nfsd4_lock use blocking locks for v4.1+ lock")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index e32ecedece0feb808567c92c1137ddcb20537d85..c107caa5652544ebadfb746663a551b022c75eb6 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -267,6 +267,8 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
        if (!nbl) {
                nbl= kmalloc(sizeof(*nbl), GFP_KERNEL);
                if (nbl) {
+                       INIT_LIST_HEAD(&nbl->nbl_list);
+                       INIT_LIST_HEAD(&nbl->nbl_lru);
                        fh_copy_shallow(&nbl->nbl_fh, fh);
                        locks_init_lock(&nbl->nbl_lock);
                        nfsd4_init_cb(&nbl->nbl_cb, lo->lo_owner.so_client,