linux-kernel - [PATCH 3/7] test_user_copy: Check __clear_user()/clear

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1438789735-4643-4-git-send-email-james.hogan@imgtec.com>
Date:	Wed, 5 Aug 2015 16:48:51 +0100
From:	James Hogan <james.hogan@...tec.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<linux-arch@...r.kernel.org>, <linux-mips@...ux-mips.org>,
	James Hogan <james.hogan@...tec.com>,
	Kees Cook <keescook@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 3/7] test_user_copy: Check __clear_user()/clear_user()

Add basic success/failure checking of __clear_user() and clear_user(),
which zero an area of user or kernel memory and return the number of
bytes left to clear.

This catches a couple of bugs in the MIPS Enhanced Virtual Memory (EVA)
implementation (which have already been fixed):
test_user_copy: legitimate kernel clear_user failed
test_user_copy: legitimate kernel __clear_user failed

Due to neither function checking the user address limit, and both
resorting to user access unconditionally.

New tests:
- legitimate clear_user
- legitimate __clear_user
- illegal kernel clear_user
- illegal kernel __clear_user
- legitimate kernel clear_user
- legitimate kernel __clear_user

Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 lib/test_user_copy.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
index 23fb9d15f50c..4ec2cfa916c1 100644
--- a/lib/test_user_copy.c
+++ b/lib/test_user_copy.c
@@ -68,6 +68,8 @@ static int __init test_user_copy_init(void)
 		    "legitimate get_user failed");
 	ret |= test(put_user(value, (unsigned long __user *)usermem),
 		    "legitimate put_user failed");
+	ret |= test(clear_user(usermem, PAGE_SIZE) != 0,
+		    "legitimate clear_user passed");
 
 	ret |= test(!access_ok(VERIFY_READ, usermem, PAGE_SIZE * 2),
 		    "legitimate access_ok VERIFY_READ failed");
@@ -81,6 +83,8 @@ static int __init test_user_copy_init(void)
 		    "legitimate __get_user failed");
 	ret |= test(__put_user(value, (unsigned long __user *)usermem),
 		    "legitimate __put_user failed");
+	ret |= test(__clear_user(usermem, PAGE_SIZE) != 0,
+		    "legitimate __clear_user passed");
 
 	/* Invalid usage: none of these should succeed. */
 	ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
@@ -99,6 +103,8 @@ static int __init test_user_copy_init(void)
 		    "illegal get_user passed");
 	ret |= test(!put_user(value, (unsigned long __user *)kmem),
 		    "illegal put_user passed");
+	ret |= test(clear_user((char __user *)kmem, PAGE_SIZE) != PAGE_SIZE,
+		    "illegal kernel clear_user passed");
 
 	/*
 	 * If unchecked user accesses (__*) on this architecture cannot access
@@ -128,6 +134,8 @@ static int __init test_user_copy_init(void)
 		    "illegal __get_user passed");
 	ret |= test(!__put_user(value, (unsigned long __user *)kmem),
 		    "illegal __put_user passed");
+	ret |= test(__clear_user((char __user *)kmem, PAGE_SIZE) != PAGE_SIZE,
+		    "illegal kernel __clear_user passed");
 #endif
 
 	/*
@@ -148,6 +156,8 @@ static int __init test_user_copy_init(void)
 		    "legitimate kernel get_user failed");
 	ret |= test(put_user(value, (unsigned long __user *)kmem),
 		    "legitimate kernel put_user failed");
+	ret |= test(clear_user((char __user *)kmem, PAGE_SIZE) != 0,
+		    "legitimate kernel clear_user failed");
 
 	ret |= test(!access_ok(VERIFY_READ, (char __user *)kmem, PAGE_SIZE * 2),
 		    "legitimate kernel access_ok VERIFY_READ failed");
@@ -164,6 +174,8 @@ static int __init test_user_copy_init(void)
 		    "legitimate kernel __get_user failed");
 	ret |= test(__put_user(value, (unsigned long __user *)kmem),
 		    "legitimate kernel __put_user failed");
+	ret |= test(__clear_user((char __user *)kmem, PAGE_SIZE) != 0,
+		    "legitimate kernel __clear_user failed");
 
 	/* Restore previous address limit. */
 	set_fs(fs);
-- 
2.3.6

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/