linux-kernel - [PATCH] scsi: advansys: use struct

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Date:   Fri, 4 Jan 2019 15:22:09 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Matthew Wilcox <willy@...radead.org>,
        Hannes Reinecke <hare@...e.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] scsi: advansys: use struct_size() in kzalloc()

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 foo {
    int stuff;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now
use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

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

diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
index d37584403c33..6c274e6e1c33 100644
--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -7576,8 +7576,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp,
 			return ASC_ERROR;
 		}
 
-		asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) +
-			use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC);
+		asc_sg_head = kzalloc(struct_size(asc_sg_head, sg_list, use_sg),
+				      GFP_ATOMIC);
 		if (!asc_sg_head) {
 			scsi_dma_unmap(scp);
 			scp->result = HOST_BYTE(DID_SOFT_ERROR);
-- 
2.20.1