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usercopy: Add tests for all get_user() sizes

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The existing test was only exercising native unsigned long size
get_user(). For completeness, we should check all sizes. But we
must skip some 32-bit architectures that don't implement a 64-bit
get_user().

These new tests actually uncovered a bug in ARM's 64-bit get_user()
zeroing.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2017-02-14 12:38:07 -08:00
parent f5f893c57e
commit 4c5d7bc637
1 changed files with 76 additions and 13 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

89
lib/test_user_copy.c
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@ -25,6 +25,23 @@
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
/*
* Several 32-bit architectures support 64-bit {get,put}_user() calls.
* As there doesn't appear to be anything that can safely determine
* their capability at compile-time, we just have to opt-out certain archs.
*/
#if BITS_PER_LONG == 64 || (!defined(CONFIG_AVR32) && \
!defined(CONFIG_BLACKFIN) && \
!defined(CONFIG_M32R) && \
!defined(CONFIG_M68K) && \
!defined(CONFIG_MICROBLAZE) && \
!defined(CONFIG_MN10300) && \
!defined(CONFIG_NIOS2) && \
!defined(CONFIG_PPC32) && \
!defined(CONFIG_SUPERH))
# define TEST_U64
#endif
#define test(condition, msg) \ #define test(condition, msg) \
({ \ ({ \
int cond = (condition); \ int cond = (condition); \
@ -40,7 +57,12 @@ static int __init test_user_copy_init(void)
char __user *usermem; char __user *usermem;
char *bad_usermem; char *bad_usermem;
unsigned long user_addr; unsigned long user_addr;
unsigned long value = 0x5A; u8 val_u8;
u16 val_u16;
u32 val_u32;
#ifdef TEST_U64
u64 val_u64;
#endif
kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL); kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
if (!kmem) if (!kmem)
@ -61,14 +83,39 @@ static int __init test_user_copy_init(void)
/* /*
* Legitimate usage: none of these copies should fail. * Legitimate usage: none of these copies should fail.
*/ */
ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE), memset(kmem, 0x3a, PAGE_SIZE * 2);
"legitimate copy_from_user failed");
ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE), ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
"legitimate copy_to_user failed"); "legitimate copy_to_user failed");
ret |= test(get_user(value, (unsigned long __user *)usermem), memset(kmem, 0x0, PAGE_SIZE);
"legitimate get_user failed"); ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
ret |= test(put_user(value, (unsigned long __user *)usermem), "legitimate copy_from_user failed");
"legitimate put_user failed"); ret |= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
"legitimate usercopy failed to copy data");
#define test_legit(size, check) \
do { \
val_##size = check; \
ret |= test(put_user(val_##size, (size __user *)usermem), \
"legitimate put_user (" #size ") failed"); \
val_##size = 0; \
ret |= test(get_user(val_##size, (size __user *)usermem), \
"legitimate get_user (" #size ") failed"); \
ret |= test(val_##size != check, \
"legitimate get_user (" #size ") failed to do copy"); \
if (val_##size != check) { \
pr_info("0x%llx != 0x%llx\n", \
(unsigned long long)val_##size, \
(unsigned long long)check); \
} \
} while (0)
test_legit(u8, 0x5a);
test_legit(u16, 0x5a5b);
test_legit(u32, 0x5a5b5c5d);
#ifdef TEST_U64
test_legit(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_legit
/* /*
* Invalid usage: none of these copies should succeed. * Invalid usage: none of these copies should succeed.
@ -105,12 +152,28 @@ static int __init test_user_copy_init(void)
PAGE_SIZE), PAGE_SIZE),
"illegal reversed copy_to_user passed"); "illegal reversed copy_to_user passed");
value = 0x5a; #define test_illegal(size, check) \
ret |= test(!get_user(value, (unsigned long __user *)kmem), do { \
"illegal get_user passed"); val_##size = (check); \
ret |= test(value != 0, "zeroing failure for illegal get_user"); ret |= test(!get_user(val_##size, (size __user *)kmem), \
ret |= test(!put_user(value, (unsigned long __user *)kmem), "illegal get_user (" #size ") passed"); \
"illegal put_user passed"); ret |= test(val_##size != (size)0, \
"zeroing failure for illegal get_user (" #size ")"); \
if (val_##size != (size)0) { \
pr_info("0x%llx != 0\n", \
(unsigned long long)val_##size); \
} \
ret |= test(!put_user(val_##size, (size __user *)kmem), \
"illegal put_user (" #size ") passed"); \
} while (0)
test_illegal(u8, 0x5a);
test_illegal(u16, 0x5a5b);
test_illegal(u32, 0x5a5b5c5d);
#ifdef TEST_U64
test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_illegal
vm_munmap(user_addr, PAGE_SIZE * 2); vm_munmap(user_addr, PAGE_SIZE * 2);
kfree(kmem); kfree(kmem);