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copy-struct-from-user-v5.4-rc4 

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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
alistair/sunxi64-5.4-dsi
Linus Torvalds 2019-10-18 18:19:04 -04:00
parent 7571438a48 f418dddffc
commit 8eb4b3b0dd
1 changed files with 28 additions and 9 deletions
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37
lib/test_user_copy.c
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@ -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 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 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):
*
* [ 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. */