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Commit 6b064857 authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

usercopy: Adjust tests to deal with SMAP/PAN 



commit f5f893c57e37ca730808cb2eee3820abd05e7507 upstream.

Under SMAP/PAN/etc, we cannot write directly to userspace memory, so
this rearranges the test bytes to get written through copy_to_user().
Additionally drops the bad copy_from_user() test that would trigger a
memcpy() against userspace on failure.

[arnd: the test module was added in 3.14, and this backported patch
       should apply cleanly on all version from 3.14 to 4.10.
       The original patch was in 4.11 on top of a context change
       I saw the bug triggered with kselftest on a 4.4.y stable kernel]

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6dc95d1f

lib/test_user_copy.c

+18 −2
Original line number Diff line number Diff line
@@ -58,7 +58,9 @@ static int __init test_user_copy_init(void) 
	usermem = (char __user *)user_addr;

	bad_usermem = (char *)user_addr;



	/* Legitimate usage: none of these should fail. */

	/*

	 * Legitimate usage: none of these copies should fail.

	 */

	ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),

		    "legitimate copy_from_user failed");

	ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
@@ -68,19 +70,33 @@ static int __init test_user_copy_init(void) 
	ret |= test(put_user(value, (unsigned long __user *)usermem),

		    "legitimate put_user failed");



	/* Invalid usage: none of these should succeed. */

	/*

	 * Invalid usage: none of these copies should succeed.

	 */



	/* Reject kernel-to-kernel copies through copy_from_user(). */

	ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),

				    PAGE_SIZE),

		    "illegal all-kernel copy_from_user passed");



#if 0

	/*

	 * When running with SMAP/PAN/etc, this will Oops the kernel

	 * due to the zeroing of userspace memory on failure. This needs

	 * to be tested in LKDTM instead, since this test module does not

	 * expect to explode.

	 */

	ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,

				    PAGE_SIZE),

		    "illegal reversed copy_from_user passed");

#endif

	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");



	ret |= test(!get_user(value, (unsigned long __user *)kmem),

		    "illegal get_user passed");

	ret |= test(!put_user(value, (unsigned long __user *)kmem),