linux-kernel - [PATCH 4.4 138/192] [PATCH 4.4 08/16] cred: Reject inodes with invalid ids in set_create_file

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Date:   Mon, 12 Sep 2016 19:00:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Seth Forshee <seth.forshee@...onical.com>,
        Serge Hallyn <serge.hallyn@...onical.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 138/192] [PATCH 4.4 08/16] cred: Reject inodes with invalid ids in set_create_file_as()

4.4-stable review patch.  If anyone has any objections, please let me know.

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


From: Seth Forshee <seth.forshee@...onical.com>

[ Upstream commit 5f65e5ca286126a60f62c8421b77c2018a482b8a ]

Using INVALID_[UG]ID for the LSM file creation context doesn't
make sense, so return an error if the inode passed to
set_create_file_as() has an invalid id.

Signed-off-by: Seth Forshee <seth.forshee@...onical.com>
Acked-by: Serge Hallyn <serge.hallyn@...onical.com>
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/cred.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -689,6 +689,8 @@ EXPORT_SYMBOL(set_security_override_from
  */
 int set_create_files_as(struct cred *new, struct inode *inode)
 {
+	if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
+		return -EINVAL;
 	new->fsuid = inode->i_uid;
 	new->fsgid = inode->i_gid;
 	return security_kernel_create_files_as(new, inode);