On Mon, 2020-03-23 at 10:55 +0300, Vasily Averin wrote:
> New struct nfsd4_blocked_lock allocated in find_or_allocate_block()
> does not initialised nbl_list and nbl_lru.
> If conflock allocation fails rollback can call list_del_init()
> access uninitialized fields and corrupt memory.
>
> Fixes: 76d348fadff5 ("nfsd: have nfsd4_lock use blocking locks for v4.1+ lock")
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 32 +++++++++++++++-----------------
> 1 file changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 369e574c5092..176ef8d24fae 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -6524,6 +6524,13 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> goto out;
> }
>
> + conflock = locks_alloc_lock();
> + if (!conflock) {
> + dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
> + status = nfserr_jukebox;
> + goto out;
> + }
> +
> nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> if (!nbl) {
> dprintk("NFSD: %s: unable to allocate block!\n", __func__);
> @@ -6542,13 +6549,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> file_lock->fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
> nfs4_transform_lock_offset(file_lock);
>
> - conflock = locks_alloc_lock();
> - if (!conflock) {
> - dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
> - status = nfserr_jukebox;
> - goto out;
> - }
> -
> if (fl_flags & FL_SLEEP) {
> nbl->nbl_time = jiffies;
> spin_lock(&nn->blocked_locks_lock);
> @@ -6581,17 +6581,15 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> status = nfserrno(err);
> break;
> }
> -out:
> - if (nbl) {
> - /* dequeue it if we queued it before */
> - if (fl_flags & FL_SLEEP) {
> - spin_lock(&nn->blocked_locks_lock);
> - list_del_init(&nbl->nbl_list);
> - list_del_init(&nbl->nbl_lru);
> - spin_unlock(&nn->blocked_locks_lock);
> - }
> - free_blocked_lock(nbl);
> + /* dequeue it if we queued it before */
> + if (fl_flags & FL_SLEEP) {
> + spin_lock(&nn->blocked_locks_lock);
> + list_del_init(&nbl->nbl_list);
> + list_del_init(&nbl->nbl_lru);
> + spin_unlock(&nn->blocked_locks_lock);
> }
> + free_blocked_lock(nbl);
> +out:
> if (nf)
> nfsd_file_put(nf);
> if (lock_stp) {
Good catch! Is there any reason not to just fix this by initializing the
list_heads in find_or_allocate_block? That seems like it'd be a simpler
fix.
--
Jeff Layton <jlayton@xxxxxxxxxx>
