[PATCH net] ice: copy last block omitted in ice_get_module_eeprom()

[Petr Oros <poros@redhat.com>]

ice_get_module_eeprom() is broken since commit e9c9692c8a81 ("ice:
Reimplement module reads used by ethtool") In this refactor,
ice_get_module_eeprom() reads the eeprom in blocks of size 8.
But the condition that should protect the buffer overflow
ignores the last block. The last block always contains zeros.
Fix adding memcpy for last block.

Bug uncovered by ethtool upstream commit 9538f384b535
("netlink: eeprom: Defer page requests to individual parsers")
After this commit, ethtool reads a block with length = 1;
to read the SFF-8024 identifier value.

unpatched driver:
$ ethtool -m enp65s0f0np0 offset 0x90 length 8
Offset          Values
------          ------
0x0090:         00 00 00 00 00 00 00 00
$ ethtool -m enp65s0f0np0 offset 0x90 length 12
Offset          Values
------          ------
0x0090:         00 00 01 a0 4d 65 6c 6c 00 00 00 00
$

$ ethtool -m enp65s0f0np0
Offset          Values
------          ------
0x0000:         11 06 06 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0010:         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0020:         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0030:         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0040:         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0050:         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0060:         00 00 00 00 00 00 00 00 00 00 00 00 00 01 08 00
0x0070:         00 10 00 00 00 00 00 00 00 00 00 00 00 00 00 00

patched driver:
$ ethtool -m enp65s0f0np0 offset 0x90 length 8
Offset          Values
------          ------
0x0090:         00 00 01 a0 4d 65 6c 6c
$ ethtool -m enp65s0f0np0 offset 0x90 length 12
Offset          Values
------          ------
0x0090:         00 00 01 a0 4d 65 6c 6c 61 6e 6f 78
$ ethtool -m enp65s0f0np0
    Identifier                                : 0x11 (QSFP28)
    Extended identifier                       : 0x00
    Extended identifier description           : 1.5W max. Power consumption
    Extended identifier description           : No CDR in TX, No CDR in RX
    Extended identifier description           : High Power Class (> 3.5 W) not enabled
    Connector                                 : 0x23 (No separable connector)
    Transceiver codes                         : 0x88 0x00 0x00 0x00 0x00 0x00 0x00 0x00
    Transceiver type                          : 40G Ethernet: 40G Base-CR4
    Transceiver type                          : 25G Ethernet: 25G Base-CR CA-N
    Encoding                                  : 0x05 (64B/66B)
    BR, Nominal                               : 25500Mbps
    Rate identifier                           : 0x00
    Length (SMF,km)                           : 0km
    Length (OM3 50um)                         : 0m
    Length (OM2 50um)                         : 0m
    Length (OM1 62.5um)                       : 0m
    Length (Copper or Active cable)           : 1m
    Transmitter technology                    : 0xa0 (Copper cable unequalized)
    Attenuation at 2.5GHz                     : 4db
    Attenuation at 5.0GHz                     : 5db
    Attenuation at 7.0GHz                     : 7db
    Attenuation at 12.9GHz                    : 10db
    ........
    ....

Fixes: e9c9692c8a81 ("ice: Reimplement module reads used by ethtool")
Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice_ethtool.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c b/drivers/net/ethernet/intel/ice/ice_ethtool.c
index b360bd8f15998b..33b2bee5cfb40f 100644
--- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
+++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
@@ -4356,6 +4356,8 @@ ice_get_module_eeprom(struct net_device *netdev,
 			/* Make sure we have enough room for the new block */
 			if ((i + SFF_READ_BLOCK_SIZE) < ee->len)
 				memcpy(data + i, value, SFF_READ_BLOCK_SIZE);
+			else if (ee->len - i > 0)
+				memcpy(data + i, value, ee->len - i);
 		}
 	}
 	return 0;
-- 
2.39.2