[PATCH] net: usb: pegasus: Proper error handing when setting pegasus' MAC address

[Petko Manolov]

Fix a bug in set_ethernet_addr() which does not take into account possible
errors (or partial reads) returned by its helpers.  This can potentially lead to
writing random data into device's MAC address registers.

Signed-off-by: Petko Manolov <petko.mano...@konsulko.com>
---
 drivers/net/usb/pegasus.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index e92cb51a2c77..25855f976c1b 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -360,28 +360,45 @@ static int write_eprom_word(pegasus_t *pegasus, __u8 
index, __u16 data)
 }
 #endif                         /* PEGASUS_WRITE_EEPROM */
 
-static inline void get_node_id(pegasus_t *pegasus, __u8 *id)
+static inline int get_node_id(pegasus_t *pegasus, u8 *id)
 {
-       int i;
-       __u16 w16;
+       int i, ret;
+       u16 w16;
 
        for (i = 0; i < 3; i++) {
-               read_eprom_word(pegasus, i, &w16);
+               ret = read_eprom_word(pegasus, i, &w16);
+               if (ret < 0)
+                       return ret;
                ((__le16 *) id)[i] = cpu_to_le16(w16);
        }
+
+       return 0;
 }
 
-static void set_ethernet_addr(pegasus_t *pegasus)
+static int set_ethernet_addr(pegasus_t *pegasus)
 {
-       __u8 node_id[6];
+       int ret;
+       u8 node_id[6];
 
        if (pegasus->features & PEGASUS_II) {
-               get_registers(pegasus, 0x10, sizeof(node_id), node_id);
+               ret = get_registers(pegasus, 0x10, sizeof(node_id), node_id);
+               if (ret < 0)
+                       goto err;
        } else {
-               get_node_id(pegasus, node_id);
-               set_registers(pegasus, EthID, sizeof(node_id), node_id);
+               ret = get_node_id(pegasus, node_id);
+               if (ret < 0)
+                       goto err;
+               ret = set_registers(pegasus, EthID, sizeof(node_id), node_id);
+               if (ret < 0)
+                       goto err;
        }
+
        memcpy(pegasus->net->dev_addr, node_id, sizeof(node_id));
+
+       return 0;
+err:
+       dev_err(&pegasus->intf->dev, "device's MAC address not set.\n");
+       return ret;
 }
 
 static inline int reset_mac(pegasus_t *pegasus)
-- 
2.28.0