crypto: atmel-sha204a - Fix potential UAF and memory leak in remove path

commit bab1adf upstream.

Unregister the hwrng to prevent new ->read() calls and flush the Atmel
I2C workqueue before teardown to prevent a potential UAF if a queued
callback runs while the device is being removed.

Drop the early return to ensure sysfs entries are removed and
->hwrng.priv is freed, preventing a memory leak.

Fixes: da001fb ("crypto: atmel-i2c - add support for SHA204A random number generator")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: toblux

drivers/crypto/atmel-sha204a.c

@@ -125,10 +125,8 @@ static void atmel_sha204a_remove(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
 
-	if (atomic_read(&i2c_priv->tfm_count)) {
-		dev_emerg(&client->dev, "Device is busy, will remove it anyhow\n");
-		return;
-	}
+	devm_hwrng_unregister(&client->dev, &i2c_priv->hwrng);
+	atmel_i2c_flush_queue();
 
 	kfree((void *)i2c_priv->hwrng.priv);
 }