netdev - [PATCH net-next] bonding: don't cast const buf in sysfs store

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Message-Id: <20180722083731.31888-1-nikolay@cumulusnetworks.com>
Date:   Sun, 22 Jul 2018 11:37:31 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     netdev@...r.kernel.org
Cc:     j.vosburgh@...il.com, vfalico@...il.com, andy@...yhouse.net,
        roopa@...ulusnetworks.com, davem@...emloft.net,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: [PATCH net-next] bonding: don't cast const buf in sysfs store

As was recently discussed [1], let's avoid casting the const buf in
bonding_sysfs_store_option and use kstrndup/kfree instead.

[1] http://lists.openwall.net/netdev/2018/07/22/25

Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
---
 drivers/net/bonding/bond_sysfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 6096440e96ea..35847250da5a 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -160,14 +160,19 @@ static ssize_t bonding_sysfs_store_option(struct device *d,
 {
 	struct bonding *bond = to_bond(d);
 	const struct bond_option *opt;
+	char *buffer_clone;
 	int ret;
 
 	opt = bond_opt_get_by_name(attr->attr.name);
 	if (WARN_ON(!opt))
 		return -ENOENT;
-	ret = bond_opt_tryset_rtnl(bond, opt->id, (char *)buffer);
+	buffer_clone = kstrndup(buffer, count, GFP_KERNEL);
+	if (!buffer_clone)
+		return -ENOMEM;
+	ret = bond_opt_tryset_rtnl(bond, opt->id, buffer_clone);
 	if (!ret)
 		ret = count;
+	kfree(buffer_clone);
 
 	return ret;
 }
-- 
2.11.0