drivers/net/ethernet/mellanox/mlx5/core/en/params.c:481 mlx5e_mpwrq_validate_xsk() error: we previously assumed 'xsk' could be null (see line 478)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   1fe4fd6f5cad346e598593af36caeadc4f5d4fa9
commit: 6470d2e7e8ed8e9dd560d8dc3e09d1100a17ee26 net/mlx5e: xsk: Use KSM for unaligned XSK
config: i386-randconfig-m021-20230102
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>

New smatch warnings:
drivers/net/ethernet/mellanox/mlx5/core/en/params.c:481 mlx5e_mpwrq_validate_xsk() error: we previously assumed 'xsk' could be null (see line 478)

Old smatch warnings:
drivers/net/ethernet/mellanox/mlx5/core/en/params.c:314 mlx5e_mpwqe_get_log_num_strides() warn: signedness bug returning '(-255)'

vim +/xsk +481 drivers/net/ethernet/mellanox/mlx5/core/en/params.c

44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  474  int mlx5e_mpwrq_validate_xsk(struct mlx5_core_dev *mdev, struct mlx5e_params *params,
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  475  			     struct mlx5e_xsk_param *xsk)
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  476  {
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  477  	u8 page_shift = mlx5e_mpwrq_page_shift(mdev, xsk);
6470d2e7e8ed8e Maxim Mikityanskiy 2022-09-29 @478  	bool unaligned = xsk ? xsk->unaligned : false;
                                                                         ^^^
Assumes xsk can be NULL

e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  479  	u16 max_mtu_pkts;
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  480  
6470d2e7e8ed8e Maxim Mikityanskiy 2022-09-29 @481  	if (!mlx5e_check_fragmented_striding_rq_cap(mdev, page_shift, xsk->unaligned))
                                                                                                                      ^^^^^
Unchecked dereference

44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  482  		return -EOPNOTSUPP;
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  483  
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  484  	if (!mlx5e_rx_mpwqe_is_linear_skb(mdev, params, xsk))
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  485  		return -EINVAL;
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  486  
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  487  	/* Current RQ length is too big for the given frame size, the
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  488  	 * needed number of WQEs exceeds the maximum.
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  489  	 */
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  490  	max_mtu_pkts = min_t(u8, MLX5E_PARAMS_MAXIMUM_LOG_RQ_SIZE,
6470d2e7e8ed8e Maxim Mikityanskiy 2022-09-29  491  			     mlx5e_mpwrq_max_log_rq_pkts(mdev, page_shift, unaligned));
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  492  	if (params->log_rq_mtu_frames > max_mtu_pkts) {
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  493  		mlx5_core_err(mdev, "Current RQ length %d is too big for XSK with given frame size %u\n",
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  494  			      1 << params->log_rq_mtu_frames, xsk->chunk_size);
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  495  		return -EINVAL;
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  496  	}
e5a3cc83d54019 Maxim Mikityanskiy 2022-09-29  497  
44f4fd03b51705 Maxim Mikityanskiy 2022-09-27  498  	return 0;
b3a131c2a1602e Tariq Toukan       2021-03-07  499  }

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