[PATCH] scsi: megaraid_sas: Use struct_size() helper

[PATCH] scsi: megaraid_sas: Use struct_size() helper

[Gustavo A. R. Silva]

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct MR_PD_CFG_SEQ_NUM_SYNC {
	...
        struct MR_PD_CFG_SEQ seq[1];
} __packed;

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) + (sizeof(struct MR_PD_CFG_SEQ) * (MAX_PHYSICAL_DEVICES - 1))

with:

struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/scsi/megaraid/megaraid_sas_fusion.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index a25b6b4b6548..56bd524dddbf 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -1191,7 +1191,7 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
 int
 megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {
 	int ret = 0;
-	u32 pd_seq_map_sz;
+	size_t pd_seq_map_sz;
 	struct megasas_cmd *cmd;
 	struct megasas_dcmd_frame *dcmd;
 	struct fusion_context *fusion = instance->ctrl_context;
@@ -1200,9 +1200,7 @@ megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {
 
 	pd_sync = (void *)fusion->pd_seq_sync[(instance->pd_seq_map_id & 1)];
 	pd_seq_h = fusion->pd_seq_phys[(instance->pd_seq_map_id & 1)];
-	pd_seq_map_sz = sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) +
-			(sizeof(struct MR_PD_CFG_SEQ) *
-			(MAX_PHYSICAL_DEVICES - 1));
+	pd_seq_map_sz = struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1);
 
 	cmd = megasas_get_cmd(instance);
 	if (!cmd) {
-- 
2.21.0

Re: [PATCH] scsi: megaraid_sas: Use struct_size() helper

[Sumit Saxena]

On Sat, Jun 8, 2019 at 12:10 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
>
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct MR_PD_CFG_SEQ_NUM_SYNC {
>         ...
>         struct MR_PD_CFG_SEQ seq[1];
> } __packed;
>
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
>
> So, replace the following form:
>
> sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) + (sizeof(struct MR_PD_CFG_SEQ) * (MAX_PHYSICAL_DEVICES - 1))
>
> with:
>
> struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1)
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>

> ---
>  drivers/scsi/megaraid/megaraid_sas_fusion.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> index a25b6b4b6548..56bd524dddbf 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> @@ -1191,7 +1191,7 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
>  int
>  megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {
>         int ret = 0;
> -       u32 pd_seq_map_sz;
> +       size_t pd_seq_map_sz;
>         struct megasas_cmd *cmd;
>         struct megasas_dcmd_frame *dcmd;
>         struct fusion_context *fusion = instance->ctrl_context;
> @@ -1200,9 +1200,7 @@ megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {
>
>         pd_sync = (void *)fusion->pd_seq_sync[(instance->pd_seq_map_id & 1)];
>         pd_seq_h = fusion->pd_seq_phys[(instance->pd_seq_map_id & 1)];
> -       pd_seq_map_sz = sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) +
> -                       (sizeof(struct MR_PD_CFG_SEQ) *
> -                       (MAX_PHYSICAL_DEVICES - 1));
> +       pd_seq_map_sz = struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1);
>
>         cmd = megasas_get_cmd(instance);
>         if (!cmd) {
> --
> 2.21.0
>

Re: [PATCH] scsi: megaraid_sas: Use struct_size() helper

[Martin K. Petersen]

Gustavo,

> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct MR_PD_CFG_SEQ_NUM_SYNC {
> 	...
>         struct MR_PD_CFG_SEQ seq[1];
> } __packed;
>
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.

Applied to 5.3/scsi-queue, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering