From 0e4358b0a0c53e51263dd21f0b20937cbe4bd257 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Tue, 2 Jul 2019 10:00:40 +0200
Subject: [PATCH] ima: always return negative code for error

commit f5e1040196dbfe14c77ce3dfe3b7b08d2d961e88 upstream.

integrity_kernel_read() returns the number of bytes read. If this is
a short read then this positive value is returned from
ima_calc_file_hash_atfm(). Currently this is only indirectly called from
ima_calc_file_hash() and this function only tests for the return value
being zero or nonzero and also doesn't forward the return value.
Nevertheless there's no point in returning a positive value as an error,
so translate a short read into -EINVAL.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index d4c7b8e1b083..7532b062be59 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -268,8 +268,11 @@ static int ima_calc_file_hash_atfm(struct file *file,
 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
 		rc = integrity_kernel_read(file, offset, rbuf[active],
 					   rbuf_len);
-		if (rc != rbuf_len)
+		if (rc != rbuf_len) {
+			if (rc >= 0)
+				rc = -EINVAL;
 			goto out3;
+		}
 
 		if (rbuf[1] && offset) {
 			/* Using two buffers, and it is not the first
-- 
2.7.4