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 e6d688817b106d6de5010752789aa1aa7b2fad72..c290e849b2ed824f7f5371420d4a319079c475a0 100644 (file)
--- a/drivers/misc/eeprom/at24.c
+++ b/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);