On Tue, 2019-03-19 at 21:54 -0700, Eric Dumazet wrote: > > 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 <pakki001@xxxxxxx> > > --- > > 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. That crossed my mind when i reviewed this patch but since this is an old issue i just put a todo aside to handle it later i think the author didn't want to deal with use-after-free here, but only wanted to keep the data structure safe against add/remove operations. Anyway all we need here is rcu_read_lock() flow = idr_find(..) mlx5_fpga_tls_flow_to_cmd(flow, cmd); rcu_read_unlock() Will fix it up in a follow up patch, Thank you Eric !! > > > + > > + 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; > > } > >