ethtool: cmis_cdb: use correct rpl size in ethtool_cmis_module_poll()

rpl is passed as a pointer to ethtool_cmis_module_poll(), so the correct
size of rpl is sizeof(*rpl) which should be just 1 byte.  Using the
pointer size instead can cause stack corruption:

Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ethtool_cmis_wait_for_cond+0xf4/0x100
CPU: 72 UID: 0 PID: 4440 Comm: kworker/72:2 Kdump: loaded Tainted: G           OE      6.11.0 kernel-patches#24
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: Dell Inc. PowerEdge R760/04GWWM, BIOS 1.6.6 09/20/2023
Workqueue: events module_flash_fw_work
Call Trace:
 <TASK>
 panic+0x339/0x360
 ? ethtool_cmis_wait_for_cond+0xf4/0x100
 ? __pfx_status_success+0x10/0x10
 ? __pfx_status_fail+0x10/0x10
 __stack_chk_fail+0x10/0x10
 ethtool_cmis_wait_for_cond+0xf4/0x100
 ethtool_cmis_cdb_execute_cmd+0x1fc/0x330
 ? __pfx_status_fail+0x10/0x10
 cmis_cdb_module_features_get+0x6d/0xd0
 ethtool_cmis_cdb_init+0x8a/0xd0
 ethtool_cmis_fw_update+0x46/0x1d0
 module_flash_fw_work+0x17/0xa0
 process_one_work+0x179/0x390
 worker_thread+0x239/0x340
 ? __pfx_worker_thread+0x10/0x10
 kthread+0xcc/0x100
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x2d/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Fixes: a39c84d ("ethtool: cmis_cdb: Add a layer for supporting CDB commands")
Reviewed-by: Andy Gospodarek <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Signed-off-by: Damodharam Ammepalli <[email protected]>
Signed-off-by: Michael Chan <[email protected]>
Signed-off-by: NipaLocal <nipa@local>

Author: damodhar-ai

net/ethtool/cmis_cdb.c

@@ -351,7 +351,7 @@ ethtool_cmis_module_poll(struct net_device *dev,
 	struct netlink_ext_ack extack = {};
 	int err;
 
-	ethtool_cmis_page_init(&page_data, 0, offset, sizeof(rpl));
+	ethtool_cmis_page_init(&page_data, 0, offset, sizeof(*rpl));
 	page_data.data = (u8 *)rpl;
 
 	err = ops->get_module_eeprom_by_page(dev, &page_data, &extack);