ima: hashing large files bug fix

Hashing files larger than INT_MAX causes process to loop.
Dependent on redefining kernel_read() offset type to loff_t.

(http://bugzilla.kernel.org/show_bug.cgi?id=13909)

Cc: stable@kernel.org
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/integrity/ima/ima_crypto.c

@@ -45,9 +45,9 @@ int ima_calc_hash(struct file *file, char *digest)
 {
 	struct hash_desc desc;
 	struct scatterlist sg[1];
-	loff_t i_size;
+	loff_t i_size, offset = 0;
 	char *rbuf;
-	int rc, offset = 0;
+	int rc;
 
 	rc = init_desc(&desc);
 	if (rc != 0)
@@ -67,6 +67,8 @@ int ima_calc_hash(struct file *file, char *digest)
 			rc = rbuf_len;
 			break;
 		}
+		if (rbuf_len == 0)
+			break;
 		offset += rbuf_len;
 		sg_init_one(sg, rbuf, rbuf_len);