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.ho...@imgtec.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Andrew Morton <a...@linux-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
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