crypto: atmel-sha204a - Fix OOM ->tfm_count leak

If memory allocation fails, decrement ->tfm_count to avoid blocking
future reads.

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

Author: toblux

drivers/crypto/atmel-sha204a.c

@@ -52,9 +52,10 @@ static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data,
 		rng->priv = 0;
 	} else {
 		work_data = kmalloc_obj(*work_data, GFP_ATOMIC);
-		if (!work_data)
+		if (!work_data) {
+			atomic_dec(&i2c_priv->tfm_count);
 			return -ENOMEM;
-
+		}
 		work_data->ctx = i2c_priv;
 		work_data->client = i2c_priv->client;