Fix os crash caused by optoe when class switch (sonic-net#413)

Why:
When the device is initially set to optoe2, there is an option ->client [1]. If echo 3>dev_class is manually set at this time, as for optoe3, option ->client [1] is meaningless but the content is still the address data of optoe2, accessing an illegal address will occur, causing the device to crash.

How:
Set option->client[1] to NULL when unregistering device

Closes: sonic-net#412

Signed-off-by: philo <philo@micasnetworks.com>
Co-authored-by: Saikrishna Arcot <sarcot@microsoft.com>

Author: philo-micas

patch/0001-fix-os-crash-caused-by-optoe-when-class-switch.patch

@@ -0,0 +1,40 @@
+From 846abadb7505c10e85a3450a7343d6a89b5ecd96 Mon Sep 17 00:00:00 2001
+From: philo <philo@micasnetworks.com>
+Date: Fri, 12 Jul 2024 11:12:58 +0800
+Subject: [PATCH] fix os crash caused by optoe when class switch
+
+---
+ drivers/misc/eeprom/optoe.c | 8 ++++++--
+ 1 file changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/misc/eeprom/optoe.c b/drivers/misc/eeprom/optoe.c
+index 9129312a1..63bb8c46a 100644
+--- a/drivers/misc/eeprom/optoe.c
++++ b/drivers/misc/eeprom/optoe.c
+@@ -941,8 +941,10 @@ static ssize_t set_dev_class(struct device *dev,
+ 	} else {
+ 		/* one-address (eg QSFP) and CMIS family */
+ 		/* if it exists, remove 0x51 i2c address */
+-		if (optoe->client[1])
++		if (optoe->client[1]) {
+ 			i2c_unregister_device(optoe->client[1]);
++			optoe->client[1] = NULL;
++		}
+ 		optoe->bin.size = ONE_ADDR_EEPROM_SIZE;
+ 		optoe->num_addresses = 1;
+ 	}
+@@ -1224,8 +1226,10 @@ static int optoe_probe(struct i2c_client *client,
+ 
+ err_struct:
+ 	if (num_addresses == 2) {
+-		if (optoe->client[1])
++		if (optoe->client[1]) {
+ 			i2c_unregister_device(optoe->client[1]);
++			optoe->client[1] = NULL;
++		}
+ 	}
+ 
+ 	kfree(optoe->writebuf);
+-- 
+2.25.1
+

patch/series

@@ -214,6 +214,9 @@ cisco-npu-disable-other-bars.patch
 # Security patch
 0001-Change-the-system.map-file-permission-only-readable-.patch
 
+# Micas patches
+0001-fix-os-crash-caused-by-optoe-when-class-switch.patch
+
 #
 #
 ############################################################