Commit f42c9702 authored by Daniel Okazaki's avatar Daniel Okazaki Committed by Bartosz Golaszewski
Browse files

eeprom: at24: fix memory corruption race condition 



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: default avatarDaniel Okazaki <dtokazaki@google.com>
Fixes: b20eb4c1 ("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: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent b3de7b43

drivers/misc/eeprom/at24.c

+9 −9
Original line number Diff line number Diff line
@@ -758,15 +758,6 @@ 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.
@@ -782,6 +773,15 @@ 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);