2023-02-14 15:36 GMT+09:00, Hangyu Hua <hbh25y@xxxxxxxxx>:
> argv needs to be free when setup_async_work fails or when the current
> process is woken up.
>
> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
> Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
> ---
>
> v2: avoid NULL pointer dereference in set_close_state_blocked_works()
> v3: avoid race condition between smb2_lock() and smb2_cancel()
> v4: use another way to avoid race condition
>
> fs/ksmbd/smb2pdu.c | 20 +++++++++++++-------
> fs/ksmbd/vfs_cache.c | 2 ++
> 2 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
> index d681f91947d9..1b517d3ca2ef 100644
> --- a/fs/ksmbd/smb2pdu.c
> +++ b/fs/ksmbd/smb2pdu.c
> @@ -6666,7 +6666,8 @@ int smb2_cancel(struct ksmbd_work *work)
> "smb2 with AsyncId %llu cancelled command = 0x%x\n",
> le64_to_cpu(hdr->Id.AsyncId),
> le16_to_cpu(chdr->Command));
> - cancel_work = iter;
> + if (iter->cancel_fn)
> + cancel_work = iter;
You have freed ->cancel_argv in smb2_lock(). Wouldn't this cause UAF
issue the below?
if (cancel_work) {
cancel_work->state = KSMBD_WORK_CANCELLED;
if (cancel_work->cancel_fn)
cancel_work->cancel_fn(cancel_work->cancel_argv);
}
> break;
> }
> spin_unlock(&conn->request_lock);
> @@ -7050,6 +7051,7 @@ int smb2_lock(struct ksmbd_work *work)
> smb2_remove_blocked_lock,
> argv);
> if (rc) {
> + kfree(argv);
> err = -ENOMEM;
> goto out;
> }
> @@ -7061,6 +7063,16 @@ int smb2_lock(struct ksmbd_work *work)
>
> ksmbd_vfs_posix_lock_wait(flock);
>
> + spin_lock(&work->conn->request_lock);
> + spin_lock(&fp->f_lock);
> + if (work->state != KSMBD_WORK_CLOSED) {
I think that this check is not needed if we don't delete entry in
set_close_state_blocked_works().
> + list_del(&work->fp_entry);
> + work->cancel_fn = NULL;
> + kfree(argv);
> + }
> + spin_unlock(&fp->f_lock);
> + spin_unlock(&work->conn->request_lock);
> +
> if (work->state != KSMBD_WORK_ACTIVE) {
> list_del(&smb_lock->llist);
> spin_lock(&work->conn->llist_lock);
> @@ -7069,9 +7081,6 @@ int smb2_lock(struct ksmbd_work *work)
> locks_free_lock(flock);
>
> if (work->state == KSMBD_WORK_CANCELLED) {
> - spin_lock(&fp->f_lock);
> - list_del(&work->fp_entry);
> - spin_unlock(&fp->f_lock);
> rsp->hdr.Status =
> STATUS_CANCELLED;
> kfree(smb_lock);
> @@ -7093,9 +7102,6 @@ int smb2_lock(struct ksmbd_work *work)
> list_del(&smb_lock->clist);
> spin_unlock(&work->conn->llist_lock);
>
> - spin_lock(&fp->f_lock);
> - list_del(&work->fp_entry);
> - spin_unlock(&fp->f_lock);
> goto retry;
> } else if (!rc) {
> spin_lock(&work->conn->llist_lock);
> diff --git a/fs/ksmbd/vfs_cache.c b/fs/ksmbd/vfs_cache.c
> index da9163b00350..761a8aa540ce 100644
> --- a/fs/ksmbd/vfs_cache.c
> +++ b/fs/ksmbd/vfs_cache.c
> @@ -372,6 +372,8 @@ static void set_close_state_blocked_works(struct
> ksmbd_file *fp)
> list_del(&cancel_work->fp_entry);
> cancel_work->state = KSMBD_WORK_CLOSED;
> cancel_work->cancel_fn(cancel_work->cancel_argv);
> + cancel_work->cancel_fn = NULL;
> + kfree(cancel_work->cancel_argv);
If we remove list_del, we don't need to do them here ? and we can
change _safe version to list_for_each().
> }
> spin_unlock(&fp->f_lock);
> }
> --
> 2.34.1
>
>
