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@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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
