netdev - [PATCH] net/802: use struct_size over open coded arithmetic

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Date:   Fri, 28 Jan 2022 08:05:41 +0000
From:   cgel.zte@...il.com
To:     davem@...emloft.net
Cc:     kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Minghao Chi <chi.minghao@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: [PATCH] net/802: use struct_size over open coded arithmetic

From: Minghao Chi (CGEL ZTE) <chi.minghao@....com.cn>

Replace zero-length array with flexible-array member and make use
of the struct_size() helper in kmalloc(). For example:

struct garp_attr {
	struct rb_node			node;
	enum garp_applicant_state	state;
	u8				type;
	u8				dlen;
	unsigned char			data[];
};

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

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Minghao Chi (CGEL ZTE) <chi.minghao@....com.cn>
---
 net/802/garp.c | 2 +-
 net/802/mrp.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/802/garp.c b/net/802/garp.c
index f6012f8e59f0..746763a76f83 100644
--- a/net/802/garp.c
+++ b/net/802/garp.c
@@ -184,7 +184,7 @@ static struct garp_attr *garp_attr_create(struct garp_applicant *app,
 			return attr;
 		}
 	}
-	attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
+	attr = kmalloc(struct_size(*attr, data, len), GFP_ATOMIC);
 	if (!attr)
 		return attr;
 	attr->state = GARP_APPLICANT_VO;
diff --git a/net/802/mrp.c b/net/802/mrp.c
index 35e04cc5390c..ce3f1b610a3f 100644
--- a/net/802/mrp.c
+++ b/net/802/mrp.c
@@ -273,7 +273,7 @@ static struct mrp_attr *mrp_attr_create(struct mrp_applicant *app,
 			return attr;
 		}
 	}
-	attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
+	attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
 	if (!attr)
 		return attr;
 	attr->state = MRP_APPLICANT_VO;
-- 
2.25.1