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usercopy: add testcases to check zeroing on failure 

During usercopy the destination buffer will be zeroed if copy_from_user()
or get_user() fails. This patch adds testcases for it. The destination
buffer is set with non-zero value before illegal copy_from_user() or
get_user() is executed and the buffer is compared to zero after usercopy
is done.

Signed-off-by: Hoeun Ryu <hoeun.ryu@gmail.com>
[kees: clarified commit log, dropped second kmalloc]
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Hoeun Ryu 2017-02-12 15:13:33 +09:00 committed by Kees Cook
parent 0c744ea4f7
commit 4fbfeb8bd6
1 changed files with 10 additions and 0 deletions
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10
lib/test_user_copy.c
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@ -69,20 +69,30 @@ static int __init test_user_copy_init(void)
"legitimate put_user failed");
/* Invalid usage: none of these should succeed. */
memset(kmem, 0x5a, PAGE_SIZE);
memset(kmem + PAGE_SIZE, 0, 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(kmem + PAGE_SIZE, 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(kmem + PAGE_SIZE, 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(kmem + PAGE_SIZE, kmem, sizeof(value)),
"zeroing failure for illegal get_user");
ret |= test(!put_user(value, (unsigned long __user *)kmem),
"illegal put_user passed");