lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 10 May 2020 03:50:46 +0000
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     Leon Romanovsky <leonro@...lanox.com>,
        "gustavoars@...nel.org" <gustavoars@...nel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net/mlx5: Replace zero-length array with flexible-array

On Thu, 2020-05-07 at 13:59 -0500, Gustavo A. R. Silva wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array
> member[1][2],
> introduced in C99:
> 
> struct foo {
>         int stuff;
>         struct boo array[];
> };
> 
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure,
> which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertently introduced[3] to the codebase from now on.
> 
> Also, notice that, dynamic memory allocations won't be affected by
> this change:
> 
> "Flexible array members have incomplete type, and so the sizeof
> operator
> may not be applied. As a quirk of the original implementation of
> zero-length arrays, sizeof evaluates to zero."[1]
> 
> sizeof(flexible-array-member) triggers a warning because flexible
> array
> members have incomplete type[1]. There are some instances of code in
> which the sizeof operator is being incorrectly/erroneously applied to
> zero-length arrays and the result is zero. Such instances may be
> hiding

hmmm, we actually have some tooling that rely on this to identify such
0 length fields .. since the structs in this file are usually auto-
generated from the hw sepcs .. now i see that these tools are broken in
our CI with this patch applied.
I guess we will need to fix them, and fix our code auto-generation
tools.
 
overall i am ok with this patch. I will apply it to mlx5-next.
and submit it upstream soom.

> some bugs. So, this work (flexible-array member conversions) will
> also
> help to get completely rid of those sorts of issues.
> 
> This issue was found with the help of Coccinelle.
> 
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
>  include/linux/mlx5/driver.h   |    2 -
>  include/linux/mlx5/mlx5_ifc.h |   66 +++++++++++++++++++++--------
> -------------
>  include/linux/mlx5/qp.h       |    2 -
>  3 files changed, 35 insertions(+), 35 deletions(-)
> 
> diff --git a/include/linux/mlx5/driver.h
> b/include/linux/mlx5/driver.h
> index 6f8f79ef829b..1a4ba36275de 100644
> --- a/include/linux/mlx5/driver.h
> +++ b/include/linux/mlx5/driver.h
> @@ -200,7 +200,7 @@ struct mlx5_rsc_debug {
>  	void		       *object;
>  	enum dbg_rsc_type	type;
>  	struct dentry	       *root;
> -	struct mlx5_field_desc	fields[0];
> +	struct mlx5_field_desc	fields[];
>  };
>  
>  enum mlx5_dev_event {
> diff --git a/include/linux/mlx5/mlx5_ifc.h
> b/include/linux/mlx5/mlx5_ifc.h
> index 69b27c7dfc3e..c55686ff6504 100644
> --- a/include/linux/mlx5/mlx5_ifc.h
> +++ b/include/linux/mlx5/mlx5_ifc.h
> @@ -1677,7 +1677,7 @@ struct mlx5_ifc_wq_bits {
>  
>  	u8         reserved_at_140[0x4c0];
>  
> -	struct mlx5_ifc_cmd_pas_bits pas[0];
> +	struct mlx5_ifc_cmd_pas_bits pas[];
>  };
>  
>  struct mlx5_ifc_rq_num_bits {
> @@ -1895,7 +1895,7 @@ struct mlx5_ifc_resource_dump_menu_segment_bits
> {
>  	u8         reserved_at_20[0x10];
>  	u8         num_of_records[0x10];
>  
> -	struct mlx5_ifc_resource_dump_menu_record_bits record[0];
> +	struct mlx5_ifc_resource_dump_menu_record_bits record[];
>  };
>  
>  struct mlx5_ifc_resource_dump_resource_segment_bits {
> @@ -1907,7 +1907,7 @@ struct
> mlx5_ifc_resource_dump_resource_segment_bits {
>  
>  	u8         index2[0x20];
>  
> -	u8         payload[0][0x20];
> +	u8         payload[][0x20];
>  };
>  
>  struct mlx5_ifc_resource_dump_terminate_segment_bits {
> @@ -2984,7 +2984,7 @@ struct mlx5_ifc_flow_context_bits {
>  
>  	u8         reserved_at_1200[0x600];
>  
> -	union mlx5_ifc_dest_format_struct_flow_counter_list_auto_bits
> destination[0];
> +	union mlx5_ifc_dest_format_struct_flow_counter_list_auto_bits
> destination[];
>  };
>  
>  enum {
> @@ -3276,7 +3276,7 @@ struct mlx5_ifc_rqtc_bits {
>  
>  	u8         reserved_at_e0[0x6a0];
>  
> -	struct mlx5_ifc_rq_num_bits rq_num[0];
> +	struct mlx5_ifc_rq_num_bits rq_num[];
>  };
>  
>  enum {
> @@ -3388,7 +3388,7 @@ struct mlx5_ifc_nic_vport_context_bits {
>  
>  	u8         reserved_at_7e0[0x20];
>  
> -	u8         current_uc_mac_address[0][0x40];
> +	u8         current_uc_mac_address[][0x40];
>  };
>  
>  enum {
> @@ -4310,7 +4310,7 @@ struct mlx5_ifc_query_xrc_srq_out_bits {
>  
>  	u8         reserved_at_280[0x600];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_query_xrc_srq_in_bits {
> @@ -4588,7 +4588,7 @@ struct mlx5_ifc_query_srq_out_bits {
>  
>  	u8         reserved_at_280[0x600];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_query_srq_in_bits {
> @@ -4799,7 +4799,7 @@ struct mlx5_ifc_query_qp_out_bits {
>  
>  	u8         reserved_at_800[0x80];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_query_qp_in_bits {
> @@ -5132,7 +5132,7 @@ struct mlx5_ifc_query_hca_vport_pkey_out_bits {
>  
>  	u8         reserved_at_40[0x40];
>  
> -	struct mlx5_ifc_pkey_bits pkey[0];
> +	struct mlx5_ifc_pkey_bits pkey[];
>  };
>  
>  struct mlx5_ifc_query_hca_vport_pkey_in_bits {
> @@ -5168,7 +5168,7 @@ struct mlx5_ifc_query_hca_vport_gid_out_bits {
>  	u8         gids_num[0x10];
>  	u8         reserved_at_70[0x10];
>  
> -	struct mlx5_ifc_array128_auto_bits gid[0];
> +	struct mlx5_ifc_array128_auto_bits gid[];
>  };
>  
>  struct mlx5_ifc_query_hca_vport_gid_in_bits {
> @@ -5436,7 +5436,7 @@ struct mlx5_ifc_query_flow_counter_out_bits {
>  
>  	u8         reserved_at_40[0x40];
>  
> -	struct mlx5_ifc_traffic_counter_bits flow_statistics[0];
> +	struct mlx5_ifc_traffic_counter_bits flow_statistics[];
>  };
>  
>  struct mlx5_ifc_query_flow_counter_in_bits {
> @@ -5530,7 +5530,7 @@ struct mlx5_ifc_query_eq_out_bits {
>  
>  	u8         reserved_at_300[0x580];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_query_eq_in_bits {
> @@ -5555,7 +5555,7 @@ struct mlx5_ifc_packet_reformat_context_in_bits
> {
>  	u8         reserved_at_20[0x10];
>  	u8         reformat_data[2][0x8];
>  
> -	u8         more_reformat_data[0][0x8];
> +	u8         more_reformat_data[][0x8];
>  };
>  
>  struct mlx5_ifc_query_packet_reformat_context_out_bits {
> @@ -5566,7 +5566,7 @@ struct
> mlx5_ifc_query_packet_reformat_context_out_bits {
>  
>  	u8         reserved_at_40[0xa0];
>  
> -	struct mlx5_ifc_packet_reformat_context_in_bits
> packet_reformat_context[0];
> +	struct mlx5_ifc_packet_reformat_context_in_bits
> packet_reformat_context[];
>  };
>  
>  struct mlx5_ifc_query_packet_reformat_context_in_bits {
> @@ -5805,7 +5805,7 @@ struct mlx5_ifc_query_cq_out_bits {
>  
>  	u8         reserved_at_280[0x600];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_query_cq_in_bits {
> @@ -6412,7 +6412,7 @@ struct mlx5_ifc_modify_cq_in_bits {
>  
>  	u8         reserved_at_300[0x580];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_modify_cong_status_out_bits {
> @@ -6476,7 +6476,7 @@ struct mlx5_ifc_manage_pages_out_bits {
>  
>  	u8         reserved_at_60[0x20];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  enum {
> @@ -6498,7 +6498,7 @@ struct mlx5_ifc_manage_pages_in_bits {
>  
>  	u8         input_num_entries[0x20];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_mad_ifc_out_bits {
> @@ -7453,7 +7453,7 @@ struct mlx5_ifc_create_xrc_srq_in_bits {
>  
>  	u8         reserved_at_300[0x580];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_create_tis_out_bits {
> @@ -7529,7 +7529,7 @@ struct mlx5_ifc_create_srq_in_bits {
>  
>  	u8         reserved_at_280[0x600];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_create_sq_out_bits {
> @@ -7690,7 +7690,7 @@ struct mlx5_ifc_create_qp_in_bits {
>  	u8         wq_umem_valid[0x1];
>  	u8         reserved_at_861[0x1f];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_create_psv_out_bits {
> @@ -7761,7 +7761,7 @@ struct mlx5_ifc_create_mkey_in_bits {
>  
>  	u8         reserved_at_320[0x560];
>  
> -	u8         klm_pas_mtt[0][0x20];
> +	u8         klm_pas_mtt[][0x20];
>  };
>  
>  enum {
> @@ -7894,7 +7894,7 @@ struct mlx5_ifc_create_eq_in_bits {
>  
>  	u8         reserved_at_3c0[0x4c0];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_create_dct_out_bits {
> @@ -7951,7 +7951,7 @@ struct mlx5_ifc_create_cq_in_bits {
>  	u8         cq_umem_valid[0x1];
>  	u8         reserved_at_2e1[0x59f];
>  
> -	u8         pas[0][0x40];
> +	u8         pas[][0x40];
>  };
>  
>  struct mlx5_ifc_config_int_moderation_out_bits {
> @@ -8307,7 +8307,7 @@ struct mlx5_ifc_access_register_out_bits {
>  
>  	u8         reserved_at_40[0x40];
>  
> -	u8         register_data[0][0x20];
> +	u8         register_data[][0x20];
>  };
>  
>  enum {
> @@ -8327,7 +8327,7 @@ struct mlx5_ifc_access_register_in_bits {
>  
>  	u8         argument[0x20];
>  
> -	u8         register_data[0][0x20];
> +	u8         register_data[][0x20];
>  };
>  
>  struct mlx5_ifc_sltp_reg_bits {
> @@ -9344,7 +9344,7 @@ struct mlx5_ifc_cmd_in_bits {
>  	u8         reserved_at_20[0x10];
>  	u8         op_mod[0x10];
>  
> -	u8         command[0][0x20];
> +	u8         command[][0x20];
>  };
>  
>  struct mlx5_ifc_cmd_if_box_bits {
> @@ -9638,7 +9638,7 @@ struct mlx5_ifc_mcqi_reg_bits {
>  	u8         reserved_at_a0[0x10];
>  	u8         data_size[0x10];
>  
> -	union mlx5_ifc_mcqi_reg_data_bits data[0];
> +	union mlx5_ifc_mcqi_reg_data_bits data[];
>  };
>  
>  struct mlx5_ifc_mcc_reg_bits {
> @@ -10200,7 +10200,7 @@ struct mlx5_ifc_umem_bits {
>  
>  	u8         num_of_mtt[0x40];
>  
> -	struct mlx5_ifc_mtt_bits  mtt[0];
> +	struct mlx5_ifc_mtt_bits  mtt[];
>  };
>  
>  struct mlx5_ifc_uctx_bits {
> @@ -10325,7 +10325,7 @@ struct mlx5_ifc_mtrc_stdb_bits {
>  	u8         reserved_at_4[0x4];
>  	u8         read_size[0x18];
>  	u8         start_offset[0x20];
> -	u8         string_db_data[0];
> +	u8         string_db_data[];
>  };
>  
>  struct mlx5_ifc_mtrc_ctrl_bits {
> @@ -10379,7 +10379,7 @@ struct mlx5_ifc_query_esw_functions_out_bits
> {
>  	struct mlx5_ifc_host_params_context_bits host_params_context;
>  
>  	u8         reserved_at_280[0x180];
> -	u8         host_sf_enable[0][0x40];
> +	u8         host_sf_enable[][0x40];
>  };
>  
>  struct mlx5_ifc_sf_partition_bits {
> @@ -10399,7 +10399,7 @@ struct mlx5_ifc_query_sf_partitions_out_bits
> {
>  
>  	u8         reserved_at_60[0x20];
>  
> -	struct mlx5_ifc_sf_partition_bits sf_partition[0];
> +	struct mlx5_ifc_sf_partition_bits sf_partition[];
>  };
>  
>  struct mlx5_ifc_query_sf_partitions_in_bits {
> diff --git a/include/linux/mlx5/qp.h b/include/linux/mlx5/qp.h
> index ae63b1ae9004..4e684298d1de 100644
> --- a/include/linux/mlx5/qp.h
> +++ b/include/linux/mlx5/qp.h
> @@ -402,7 +402,7 @@ struct mlx5_wqe_signature_seg {
>  
>  struct mlx5_wqe_inline_seg {
>  	__be32	byte_count;
> -	__be32	data[0];
> +	__be32	data[];
>  };
>  
>  enum mlx5_sig_type {
> 

Powered by blists - more mailing lists