eeprom: at24: fix memory corruption race condition

jira LE-1907
cve CVE-2024-35848
Rebuild_History Non-Buildable kernel-5.14.0-427.31.1.el9_4
commit-author Daniel Okazaki <dtokazaki@google.com>
commit f42c970

If the eeprom is not accessible, an nvmem device will be registered, the
read will fail, and the device will be torn down. If another driver
accesses the nvmem device after the teardown, it will reference
invalid memory.

Move the failure point before registering the nvmem device.

	Signed-off-by: Daniel Okazaki <dtokazaki@google.com>
Fixes: b20eb4c ("eeprom: at24: drop unnecessary label")
	Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240422174337.2487142-1-dtokazaki@google.com
	Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
(cherry picked from commit f42c970)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

drivers/misc/eeprom/at24.c

@@ -781,15 +781,6 @@ static int at24_probe(struct i2c_client *client)
 	}
 	pm_runtime_enable(dev);
 
-	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
-	if (IS_ERR(at24->nvmem)) {
-		pm_runtime_disable(dev);
-		if (!pm_runtime_status_suspended(dev))
-			regulator_disable(at24->vcc_reg);
-		return dev_err_probe(dev, PTR_ERR(at24->nvmem),
-				     "failed to register nvmem\n");
-	}
-
 	/*
 	 * Perform a one-byte test read to verify that the chip is functional,
 	 * unless powering on the device is to be avoided during probe (i.e.
@@ -805,6 +796,15 @@ static int at24_probe(struct i2c_client *client)
 		}
 	}
 
+	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
+	if (IS_ERR(at24->nvmem)) {
+		pm_runtime_disable(dev);
+		if (!pm_runtime_status_suspended(dev))
+			regulator_disable(at24->vcc_reg);
+		return dev_err_probe(dev, PTR_ERR(at24->nvmem),
+				     "failed to register nvmem\n");
+	}
+
 	/* If this a SPD EEPROM, probe for DDR3 thermal sensor */
 	if (cdata == &at24_data_spd)
 		at24_probe_temp_sensor(client);