Subject: Re: [Intel-wired-lan] [PATCH] overflow: Add struct_size_t() helper

From: "Gustavo A. R. Silva" <[email-masked]>
Date: Mon, 22 May 2023 15:34:25 -0600

On Mon, May 22, 2023 at 02:18:13PM -0700, Kees Cook wrote:
> While struct_size() is normally used in situations where the structure
> type already has a pointer instance, there are places where no variable
> is available. In the past, this has been worked around by using a typed
> NULL first argument, but this is a bit ugly. Add a helper to do this,
> and replace the handful of instances of the code pattern with it.
> 
> Instances were found with this Coccinelle script:
> 
> @struct_size_t@
> identifier STRUCT, MEMBER;
> expression COUNT;
> @@
> 
> -       struct_size((struct STRUCT *)\(0\|NULL\),
> +       struct_size_t(struct STRUCT,
>                 MEMBER, COUNT)

This indeed was much needed.

Plus, we save 3 characters on each line. :D

> 
> Suggested-by: Christoph Hellwig <[email-masked]>
> Cc: Jesse Brandeburg <[email-masked]>
> Cc: Tony Nguyen <[email-masked]>
> Cc: "David S. Miller" <[email-masked]>
> Cc: Eric Dumazet <[email-masked]>
> Cc: Jakub Kicinski <[email-masked]>
> Cc: Paolo Abeni <[email-masked]>
> Cc: James Smart <[email-masked]>
> Cc: Keith Busch <[email-masked]>
> Cc: Jens Axboe <[email-masked]>
> Cc: Sagi Grimberg <[email-masked]>
> Cc: HighPoint Linux Team <[email-masked]>
> Cc: "James E.J. Bottomley" <[email-masked]>
> Cc: "Martin K. Petersen" <[email-masked]>
> Cc: Kashyap Desai <[email-masked]>
> Cc: Sumit Saxena <[email-masked]>
> Cc: Shivasharan S <[email-masked]>
> Cc: Don Brace <[email-masked]>
> Cc: "Darrick J. Wong" <[email-masked]>
> Cc: Dave Chinner <[email-masked]>
> Cc: Guo Xuenan <[email-masked]>
> Cc: Gwan-gyeong Mun <[email-masked]>
> Cc: Nick Desaulniers <[email-masked]>
> Cc: Daniel Latypov <[email-masked]>
> Cc: kernel test robot <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Signed-off-by: Kees Cook <[email-masked]>

Reviewed-by: Gustavo A. R. Silva <[email-masked]>

Thanks!
--
Gustavo

> ---
> Unless there are objections, I'll just take this via my tree...
> ---
>  drivers/net/ethernet/intel/ice/ice_ddp.h  |  9 ++++-----
>  drivers/nvme/host/fc.c                    |  8 ++++----
>  drivers/scsi/hptiop.c                     |  4 ++--
>  drivers/scsi/megaraid/megaraid_sas_base.c | 12 ++++++------
>  drivers/scsi/megaraid/megaraid_sas_fp.c   |  6 +++---
>  drivers/scsi/smartpqi/smartpqi_init.c     |  2 +-
>  fs/xfs/libxfs/xfs_btree.h                 |  2 +-
>  fs/xfs/scrub/btree.h                      |  2 +-
>  include/linux/overflow.h                  | 18 +++++++++++++++++-
>  lib/overflow_kunit.c                      |  2 +-
>  10 files changed, 40 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_ddp.h b/drivers/net/ethernet/intel/ice/ice_ddp.h
> index 37eadb3d27a8..41acfe26df1c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ddp.h
> +++ b/drivers/net/ethernet/intel/ice/ice_ddp.h
> @@ -185,7 +185,7 @@ struct ice_buf_hdr {
>  
>  #define ICE_MAX_ENTRIES_IN_BUF(hd_sz, ent_sz)                                 \
>  	((ICE_PKG_BUF_SIZE -                                                  \
> -	  struct_size((struct ice_buf_hdr *)0, section_entry, 1) - (hd_sz)) / \
> +	  struct_size_t(struct ice_buf_hdr,  section_entry, 1) - (hd_sz)) / \
>  	 (ent_sz))
>  
>  /* ice package section IDs */
> @@ -297,7 +297,7 @@ struct ice_label_section {
>  };
>  
>  #define ICE_MAX_LABELS_IN_BUF                                             \
> -	ICE_MAX_ENTRIES_IN_BUF(struct_size((struct ice_label_section *)0, \
> +	ICE_MAX_ENTRIES_IN_BUF(struct_size_t(struct ice_label_section,  \
>  					   label, 1) -                    \
>  				       sizeof(struct ice_label),          \
>  			       sizeof(struct ice_label))
> @@ -352,7 +352,7 @@ struct ice_boost_tcam_section {
>  };
>  
>  #define ICE_MAX_BST_TCAMS_IN_BUF                                               \
> -	ICE_MAX_ENTRIES_IN_BUF(struct_size((struct ice_boost_tcam_section *)0, \
> +	ICE_MAX_ENTRIES_IN_BUF(struct_size_t(struct ice_boost_tcam_section,  \
>  					   tcam, 1) -                          \
>  				       sizeof(struct ice_boost_tcam_entry),    \
>  			       sizeof(struct ice_boost_tcam_entry))
> @@ -372,8 +372,7 @@ struct ice_marker_ptype_tcam_section {
>  };
>  
>  #define ICE_MAX_MARKER_PTYPE_TCAMS_IN_BUF                                    \
> -	ICE_MAX_ENTRIES_IN_BUF(                                              \
> -		struct_size((struct ice_marker_ptype_tcam_section *)0, tcam, \
> +	ICE_MAX_ENTRIES_IN_BUF(struct_size_t(struct ice_marker_ptype_tcam_section,  tcam, \
>  			    1) -                                             \
>  			sizeof(struct ice_marker_ptype_tcam_entry),          \
>  		sizeof(struct ice_marker_ptype_tcam_entry))
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 2ed75923507d..691f2df574ce 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -2917,8 +2917,8 @@ nvme_fc_create_io_queues(struct nvme_fc_ctrl *ctrl)
>  
>  	ret = nvme_alloc_io_tag_set(&ctrl->ctrl, &ctrl->tag_set,
>  			&nvme_fc_mq_ops, 1,
> -			struct_size((struct nvme_fcp_op_w_sgl *)NULL, priv,
> -				    ctrl->lport->ops->fcprqst_priv_sz));
> +			struct_size_t(struct nvme_fcp_op_w_sgl, priv,
> +				      ctrl->lport->ops->fcprqst_priv_sz));
>  	if (ret)
>  		return ret;
>  
> @@ -3536,8 +3536,8 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
>  
>  	ret = nvme_alloc_admin_tag_set(&ctrl->ctrl, &ctrl->admin_tag_set,
>  			&nvme_fc_admin_mq_ops,
> -			struct_size((struct nvme_fcp_op_w_sgl *)NULL, priv,
> -				    ctrl->lport->ops->fcprqst_priv_sz));
> +			struct_size_t(struct nvme_fcp_op_w_sgl, priv,
> +				      ctrl->lport->ops->fcprqst_priv_sz));
>  	if (ret)
>  		goto fail_ctrl;
>  
> diff --git a/drivers/scsi/hptiop.c b/drivers/scsi/hptiop.c
> index 06ccb51bf6a9..f5334ccbf2ca 100644
> --- a/drivers/scsi/hptiop.c
> +++ b/drivers/scsi/hptiop.c
> @@ -1394,8 +1394,8 @@ static int hptiop_probe(struct pci_dev *pcidev, const struct pci_device_id *id)
>  	host->cmd_per_lun = le32_to_cpu(iop_config.max_requests);
>  	host->max_cmd_len = 16;
>  
> -	req_size = struct_size((struct hpt_iop_request_scsi_command *)0,
> -			       sg_list, hba->max_sg_descriptors);
> +	req_size = struct_size_t(struct hpt_iop_request_scsi_command,
> +				 sg_list, hba->max_sg_descriptors);
>  	if ((req_size & 0x1f) != 0)
>  		req_size = (req_size + 0x1f) & ~0x1f;
>  
> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index 317c944c68e3..050eed8e2684 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -5153,8 +5153,8 @@ static void megasas_update_ext_vd_details(struct megasas_instance *instance)
>  		fusion->max_map_sz = ventura_map_sz;
>  	} else {
>  		fusion->old_map_sz =
> -			struct_size((struct MR_FW_RAID_MAP *)0, ldSpanMap,
> -				    instance->fw_supported_vd_count);
> +			struct_size_t(struct MR_FW_RAID_MAP, ldSpanMap,
> +				      instance->fw_supported_vd_count);
>  		fusion->new_map_sz =  sizeof(struct MR_FW_RAID_MAP_EXT);
>  
>  		fusion->max_map_sz =
> @@ -5789,8 +5789,8 @@ megasas_setup_jbod_map(struct megasas_instance *instance)
>  	struct fusion_context *fusion = instance->ctrl_context;
>  	size_t pd_seq_map_sz;
>  
> -	pd_seq_map_sz = struct_size((struct MR_PD_CFG_SEQ_NUM_SYNC *)0, seq,
> -				    MAX_PHYSICAL_DEVICES);
> +	pd_seq_map_sz = struct_size_t(struct MR_PD_CFG_SEQ_NUM_SYNC, seq,
> +				      MAX_PHYSICAL_DEVICES);
>  
>  	instance->use_seqnum_jbod_fp =
>  		instance->support_seqnum_jbod_fp;
> @@ -8033,8 +8033,8 @@ static void megasas_detach_one(struct pci_dev *pdev)
>  	if (instance->adapter_type != MFI_SERIES) {
>  		megasas_release_fusion(instance);
>  		pd_seq_map_sz =
> -			struct_size((struct MR_PD_CFG_SEQ_NUM_SYNC *)0,
> -				    seq, MAX_PHYSICAL_DEVICES);
> +			struct_size_t(struct MR_PD_CFG_SEQ_NUM_SYNC,
> +				      seq, MAX_PHYSICAL_DEVICES);
>  		for (i = 0; i < 2 ; i++) {
>  			if (fusion->ld_map[i])
>  				dma_free_coherent(&instance->pdev->dev,
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fp.c b/drivers/scsi/megaraid/megaraid_sas_fp.c
> index 4463a538102a..b8b388a4e28f 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fp.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fp.c
> @@ -326,9 +326,9 @@ u8 MR_ValidateMapInfo(struct megasas_instance *instance, u64 map_id)
>  	else if (instance->supportmax256vd)
>  		expected_size = sizeof(struct MR_FW_RAID_MAP_EXT);
>  	else
> -		expected_size = struct_size((struct MR_FW_RAID_MAP *)0,
> -					    ldSpanMap,
> -					    le16_to_cpu(pDrvRaidMap->ldCount));
> +		expected_size = struct_size_t(struct MR_FW_RAID_MAP,
> +					      ldSpanMap,
> +					      le16_to_cpu(pDrvRaidMap->ldCount));
>  
>  	if (le32_to_cpu(pDrvRaidMap->totalSize) != expected_size) {
>  		dev_dbg(&instance->pdev->dev, "megasas: map info structure size 0x%x",
> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
> index 03de97cd72c2..f4e0aa262164 100644
> --- a/drivers/scsi/smartpqi/smartpqi_init.c
> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
> @@ -5015,7 +5015,7 @@ static int pqi_create_queues(struct pqi_ctrl_info *ctrl_info)
>  }
>  
>  #define PQI_REPORT_EVENT_CONFIG_BUFFER_LENGTH	\
> -	struct_size((struct pqi_event_config *)0, descriptors, PQI_MAX_EVENT_DESCRIPTORS)
> +	struct_size_t(struct pqi_event_config,  descriptors, PQI_MAX_EVENT_DESCRIPTORS)
>  
>  static int pqi_configure_events(struct pqi_ctrl_info *ctrl_info,
>  	bool enable_events)
> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> index a2aa36b23e25..4d68a58be160 100644
> --- a/fs/xfs/libxfs/xfs_btree.h
> +++ b/fs/xfs/libxfs/xfs_btree.h
> @@ -301,7 +301,7 @@ struct xfs_btree_cur
>  static inline size_t
>  xfs_btree_cur_sizeof(unsigned int nlevels)
>  {
> -	return struct_size((struct xfs_btree_cur *)NULL, bc_levels, nlevels);
> +	return struct_size_t(struct xfs_btree_cur, bc_levels, nlevels);
>  }
>  
>  /* cursor flags */
> diff --git a/fs/xfs/scrub/btree.h b/fs/xfs/scrub/btree.h
> index 9d7b9ee8bef4..c32b5fad6174 100644
> --- a/fs/xfs/scrub/btree.h
> +++ b/fs/xfs/scrub/btree.h
> @@ -60,7 +60,7 @@ struct xchk_btree {
>  static inline size_t
>  xchk_btree_sizeof(unsigned int nlevels)
>  {
> -	return struct_size((struct xchk_btree *)NULL, lastkey, nlevels - 1);
> +	return struct_size_t(struct xchk_btree, lastkey, nlevels - 1);
>  }
>  
>  int xchk_btree(struct xfs_scrub *sc, struct xfs_btree_cur *cur,
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> index 0e33b5cbdb9f..f9b60313eaea 100644
> --- a/include/linux/overflow.h
> +++ b/include/linux/overflow.h
> @@ -283,7 +283,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
>   * @member: Name of the array member.
>   * @count: Number of elements in the array.
>   *
> - * Calculates size of memory needed for structure @p followed by an
> + * Calculates size of memory needed for structure of @p followed by an
>   * array of @count number of @member elements.
>   *
>   * Return: number of bytes needed or SIZE_MAX on overflow.
> @@ -293,4 +293,20 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
>  		sizeof(*(p)) + flex_array_size(p, member, count),	\
>  		size_add(sizeof(*(p)), flex_array_size(p, member, count)))
>  
> +/**
> + * struct_size_t() - Calculate size of structure with trailing flexible array
> + * @type: structure type name.
> + * @member: Name of the array member.
> + * @count: Number of elements in the array.
> + *
> + * Calculates size of memory needed for structure @type followed by an
> + * array of @count number of @member elements. Prefer using struct_size()
> + * when possible instead, to keep calculations associated with a specific
> + * instance variable of type @type.
> + *
> + * Return: number of bytes needed or SIZE_MAX on overflow.
> + */
> +#define struct_size_t(type, member, count)					\
> +	struct_size((type *)NULL, member, count)
> +
>  #endif /* __LINUX_OVERFLOW_H */
> diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c
> index dcd3ba102db6..34db0b3aa502 100644
> --- a/lib/overflow_kunit.c
> +++ b/lib/overflow_kunit.c
> @@ -649,7 +649,7 @@ struct __test_flex_array {
>  static void overflow_size_helpers_test(struct kunit *test)
>  {
>  	/* Make sure struct_size() can be used in a constant expression. */
> -	u8 ce_array[struct_size((struct __test_flex_array *)0, data, 55)];
> +	u8 ce_array[struct_size_t(struct __test_flex_array, data, 55)];
>  	struct __test_flex_array *obj;
>  	int count = 0;
>  	int var;
> -- 
> 2.34.1
> 
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