linux-kernel - [PATCH] net: ethernet: Fixe issue in nvmem_get_mac

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Message-ID: <01100196adabd0d2-24bf9783-b3d5-4566-9f98-9eda0c1f4833-000000@eu-north-1.amazonses.com>
Date: Thu, 8 May 2025 02:14:00 +0000
From: Ozgur Kara <ozgur@...sey.org>
To: "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Simon Horman <horms@...nel.org>, 
	Nikolay Aleksandrov <razor@...ckwall.org>, 
	Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] net: ethernet: Fixe issue in nvmem_get_mac_address() where
 invalid mac addresses

From: Ozgur Karatas <ozgur@...sey.org>

it's necessary to log error returned from
fwnode_property_read_u8_array because there is no detailed information
when addr returns an invalid mac address.

kfree(mac) should actually be marked as kfree((void *)mac) because mac
pointer is of type const void * and type conversion is required so
data returned from nvmem_cell_read() is of same type.

This patch fixes the issue in nvmem_get_mac_address() where invalid
mac addresses could be read due to improper error handling.

Signed-off-by: Ozgur Karatas <ozgur@...sey.org>

---
 net/ethernet/eth.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 4e3651101b86..1c5649b956e9 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -549,12 +549,12 @@ int nvmem_get_mac_address(struct device *dev,
void *addrbuf)
                return PTR_ERR(mac);

        if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
-               kfree(mac);
+               kfree((void *)mac);
                return -EINVAL;
        }

        ether_addr_copy(addrbuf, mac);
-       kfree(mac);
+       kfree((void *)mac);

        return 0;
 }
@@ -565,11 +565,16 @@ static int fwnode_get_mac_addr(struct
fwnode_handle *fwnode,
        int ret;

        ret = fwnode_property_read_u8_array(fwnode, name, addr, ETH_ALEN);
-       if (ret)
+       if (ret) {
+               pr_err("Failed to read MAC address property %s\n", name);
                return ret;
+        }

-       if (!is_valid_ether_addr(addr))
+       if (!is_valid_ether_addr(addr)) {
+               pr_err("Invalid MAC address read for %s\n", name);
                return -EINVAL;
+        }
+
        return 0;
 }

--
2.39.5