eeprom: at24: fix memory corruption race condition

[ Upstream commit f42c97027fb75776e2e9358d16bf4a99aeb04cf2 ]

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: b20eb4c1f026 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 65a7517c031a7b697c333baced28bde93ceb7042..02bea443694352eb49f7bac8aac35b1482754b8e 100644 (file)
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -782,15 +782,6 @@ static int at24_probe(struct i2c_client *client)
        pm_runtime_set_active(dev);
        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.
@@ -803,6 +794,15 @@ static int at24_probe(struct i2c_client *client)
                return -ENODEV;
        }
 
+       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);