linux-hardening - [PATCH][net-next] net: bridge: Use array_size() helper in copy_to

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Date:   Tue, 28 Sep 2021 15:12:39 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][net-next] net: bridge: Use array_size() helper in
 copy_to_user()

Use array_size() helper instead of the open-coded version in
copy_to_user(). These sorts of multiplication factors need
to be wrapped in array_size().

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 net/bridge/br_ioctl.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 793b0db9d9a3..49c268871fc1 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -71,7 +71,8 @@ static int get_fdb_entries(struct net_bridge *br, void __user *userbuf,
 
 	num = br_fdb_fillbuf(br, buf, maxnum, offset);
 	if (num > 0) {
-		if (copy_to_user(userbuf, buf, num*sizeof(struct __fdb_entry)))
+		if (copy_to_user(userbuf, buf,
+				 array_size(num, sizeof(struct __fdb_entry))))
 			num = -EFAULT;
 	}
 	kfree(buf);
@@ -188,7 +189,7 @@ int br_dev_siocdevprivate(struct net_device *dev, struct ifreq *rq, void __user
 			return -ENOMEM;
 
 		get_port_ifindices(br, indices, num);
-		if (copy_to_user(argp, indices, num * sizeof(int)))
+		if (copy_to_user(argp, indices, array_size(num, sizeof(int))))
 			num =  -EFAULT;
 		kfree(indices);
 		return num;
@@ -336,7 +337,8 @@ static int old_deviceless(struct net *net, void __user *uarg)
 
 		args[2] = get_bridge_ifindices(net, indices, args[2]);
 
-		ret = copy_to_user(uarg, indices, args[2]*sizeof(int))
+		ret = copy_to_user(uarg, indices,
+				   array_size(args[2], sizeof(int)))
 			? -EFAULT : args[2];
 
 		kfree(indices);
-- 
2.27.0