From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v4] net: mlx5: Add a missing check on idr_find, free buf Date: Tue, 19 Mar 2019 21:54:10 -0700 Message-ID: References: <20190319214244.20212-1-pakki001@umn.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190319214244.20212-1-pakki001@umn.edu> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Aditya Pakki Cc: kjlu@umn.edu, Boris Pismenny , Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Ilya Lesokhin , Wei Yongjun , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-rdma@vger.kernel.org On 03/19/2019 02:42 PM, Aditya Pakki wrote: > idr_find() can return a NULL value to 'flow' which is used without a > check. The patch adds a check to avoid potential NULL pointer dereference. > > In case of mlx5_fpga_sbu_conn_sendmsg() failure, free buf allocated > using kzalloc. > > Fixes: ab412e1dd7db ("net/mlx5: Accel, add TLS rx offload routines") > --- > v3: Reorder buf allocations and flow check. > v2: failure to return in case of flow failure. > v1: Failed to free buf in case of flow failure. > > Signed-off-by: Aditya Pakki > --- > drivers/net/ethernet/mellanox/mlx5/core/fpga/tls.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fpga/tls.c b/drivers/net/ethernet/mellanox/mlx5/core/fpga/tls.c > index 5cf5f2a9d51f..8de64e88c670 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/fpga/tls.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/fpga/tls.c > @@ -217,15 +217,21 @@ int mlx5_fpga_tls_resync_rx(struct mlx5_core_dev *mdev, u32 handle, u32 seq, > void *cmd; > int ret; > > + rcu_read_lock(); > + flow = idr_find(&mdev->fpga->tls->rx_idr, ntohl(handle)); > + rcu_read_unlock(); This looks suspect (even before your patch) What prevents flow from disappearing after this rcu_read_lock() ? IMO your patch might prevent a NULL deref, but not use-after-free. > + > + if (!flow) { > + WARN_ONCE(1, "Received NULL pointer for handle\n"); > + return -EINVAL; > + } > + > buf = kzalloc(size, GFP_ATOMIC); > if (!buf) > return -ENOMEM; > > cmd = (buf + 1); > > - rcu_read_lock(); > - flow = idr_find(&mdev->fpga->tls->rx_idr, ntohl(handle)); > - rcu_read_unlock(); > mlx5_fpga_tls_flow_to_cmd(flow, cmd); > > MLX5_SET(tls_cmd, cmd, swid, ntohl(handle)); > @@ -238,6 +244,8 @@ int mlx5_fpga_tls_resync_rx(struct mlx5_core_dev *mdev, u32 handle, u32 seq, > buf->complete = mlx_tls_kfree_complete; > > ret = mlx5_fpga_sbu_conn_sendmsg(mdev->fpga->tls->conn, buf); > + if (ret < 0) > + kfree(buf); > > return ret; > } >