linux-kernel - [PATCH 3.16 01/47] eCryptfs: fix a couple type promotion bugs

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Message-ID: <lsq.1572026582.20915405@decadent.org.uk>
Date:   Fri, 25 Oct 2019 19:03:02 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Tyler Hicks" <tyhicks@...onical.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH 3.16 01/47] eCryptfs: fix a couple type promotion bugs

3.16.76-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 0bdf8a8245fdea6f075a5fede833a5fcf1b3466c upstream.

ECRYPTFS_SIZE_AND_MARKER_BYTES is type size_t, so if "rc" is negative
that gets type promoted to a high positive value and treated as success.

Fixes: 778aeb42a708 ("eCryptfs: Cleanup and optimize ecryptfs_lookup_interpose()")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
[tyhicks: Use "if/else if" rather than "if/if"]
Signed-off-by: Tyler Hicks <tyhicks@...onical.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/ecryptfs/crypto.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1042,8 +1042,10 @@ int ecryptfs_read_and_validate_header_re
 
 	rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
 				 inode);
-	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
-		return rc >= 0 ? -EINVAL : rc;
+	if (rc < 0)
+		return rc;
+	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
+		return -EINVAL;
 	rc = ecryptfs_validate_marker(marker);
 	if (!rc)
 		ecryptfs_i_size_init(file_size, inode);
@@ -1401,8 +1403,10 @@ int ecryptfs_read_and_validate_xattr_reg
 	rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
 				     ECRYPTFS_XATTR_NAME, file_size,
 				     ECRYPTFS_SIZE_AND_MARKER_BYTES);
-	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
-		return rc >= 0 ? -EINVAL : rc;
+	if (rc < 0)
+		return rc;
+	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
+		return -EINVAL;
 	rc = ecryptfs_validate_marker(marker);
 	if (!rc)
 		ecryptfs_i_size_init(file_size, inode);