Commit 8eb4b3b0 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'copy-struct-from-user-v5.4-rc4' of... 

Merge tag 'copy-struct-from-user-v5.4-rc4' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux

Pull usercopy test fixlets from Christian Brauner:
 "This contains two improvements for the copy_struct_from_user() tests:

   - a coding style change to get rid of the ugly "if ((ret |= test()))"
     pointed out when pulling the original patchset.

   - avoid a soft lockups when running the usercopy tests on machines
     with large page sizes by scanning only a 1024 byte region"

* tag 'copy-struct-from-user-v5.4-rc4' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux:
  usercopy: Avoid soft lockups in test_check_nonzero_user()
  lib: test_user_copy: style cleanup
parents 7571438a f418dddf

lib/test_user_copy.c

+28 −9
Original line number Diff line number Diff line
@@ -47,18 +47,35 @@ static bool is_zeroed(void *from, size_t size) 
static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)

{

	int ret = 0;

	size_t start, end, i;

	size_t zero_start = size / 4;

	size_t zero_end = size - zero_start;

	size_t start, end, i, zero_start, zero_end;



	if (test(size < 2 * PAGE_SIZE, "buffer too small"))

		return -EINVAL;



	/*

	 * We want to cross a page boundary to exercise the code more

	 * effectively. We also don't want to make the size we scan too large,

	 * otherwise the test can take a long time and cause soft lockups. So

	 * scan a 1024 byte region across the page boundary.

	 */

	size = 1024;

	start = PAGE_SIZE - (size / 2);



	kmem += start;

	umem += start;



	zero_start = size / 4;

	zero_end = size - zero_start;



	/*

	 * We conduct a series of check_nonzero_user() tests on a block of memory

	 * with the following byte-pattern (trying every possible [start,end]

	 * pair):

	 * We conduct a series of check_nonzero_user() tests on a block of

	 * memory with the following byte-pattern (trying every possible

	 * [start,end] pair):

	 *

	 *   [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]

	 *

	 * And we verify that check_nonzero_user() acts identically to memchr_inv().

	 * And we verify that check_nonzero_user() acts identically to

	 * memchr_inv().

	 */



	memset(kmem, 0x0, size);
@@ -93,11 +110,13 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem, 
	size_t ksize, usize;



	umem_src = kmalloc(size, GFP_KERNEL);

	if ((ret |= test(umem_src == NULL, "kmalloc failed")))

	ret = test(umem_src == NULL, "kmalloc failed");

	if (ret)

		goto out_free;



	expected = kmalloc(size, GFP_KERNEL);

	if ((ret |= test(expected == NULL, "kmalloc failed")))

	ret = test(expected == NULL, "kmalloc failed");

	if (ret)

		goto out_free;



	/* Fill umem with a fixed byte pattern. */

CRA Git | Maintained and supported by SUSTech CRA and CCSE