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Date: Sun, 12 Feb 2017 15:13:33 +0900
From: Hoeun Ryu <hoeun.ryu@...il.com>
To: Kees Cook <keescook@...omium.org>
Cc: linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Hoeun Ryu <hoeun.ryu@...il.com>
Subject: [PATCH] usercopy: add testcases to check zeroing on failure of usercopy
In the hardend usercopy, the destination buffer will be zeroed if
copy_from_user/get_user fails. This patch adds testcases for it.
The destination buffer is set with non-zero value before illegal
copy_from_user/get_user is executed and the buffer is compared to
zero after usercopy is done.
Signed-off-by: Hoeun Ryu <hoeun.ryu@...il.com>
---
lib/test_user_copy.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
index 0ecef3e..54bd898 100644
--- a/lib/test_user_copy.c
+++ b/lib/test_user_copy.c
@@ -41,11 +41,18 @@ static int __init test_user_copy_init(void)
char *bad_usermem;
unsigned long user_addr;
unsigned long value = 0x5A;
+ char *zerokmem;
kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
if (!kmem)
return -ENOMEM;
+ zerokmem = kzalloc(PAGE_SIZE * 2, GFP_KERNEL);
+ if (!zerokmem) {
+ kfree(kmem);
+ return -ENOMEM;
+ }
+
user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_PRIVATE, 0);
@@ -69,25 +76,35 @@ static int __init test_user_copy_init(void)
"legitimate put_user failed");
/* Invalid usage: none of these should succeed. */
+ memset(kmem, 0x5A, PAGE_SIZE);
ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
PAGE_SIZE),
"illegal all-kernel copy_from_user passed");
+ ret |= test(memcmp(zerokmem, kmem, PAGE_SIZE),
+ "zeroing failure for illegal all-kernel copy_from_user");
+ memset(bad_usermem, 0x5A, PAGE_SIZE);
ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,
PAGE_SIZE),
"illegal reversed copy_from_user passed");
+ ret |= test(memcmp(zerokmem, bad_usermem, PAGE_SIZE),
+ "zeroing failure for illegal reversed copy_from_user");
ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
PAGE_SIZE),
"illegal all-kernel copy_to_user passed");
ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
PAGE_SIZE),
"illegal reversed copy_to_user passed");
+ memset(kmem, 0x5A, PAGE_SIZE);
ret |= test(!get_user(value, (unsigned long __user *)kmem),
"illegal get_user passed");
+ ret |= test(memcmp(zerokmem, kmem, sizeof(value)),
+ "zeroing failure for illegal get_user");
ret |= test(!put_user(value, (unsigned long __user *)kmem),
"illegal put_user passed");
vm_munmap(user_addr, PAGE_SIZE * 2);
kfree(kmem);
+ kfree(zerokmem);
if (ret == 0) {
pr_info("tests passed.\n");
--
2.7.4
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