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mm/kfence: add a new kunit test test_use_after_free_read_nofault()

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Faults from copy_from_kernel_nofault() need to be handled by fixup table
and should not be handled by kfence.  Otherwise while reading /proc/kcore
which uses copy_from_kernel_nofault(), kfence can generate false
negatives.  This can happen when /proc/kcore ends up reading an unmapped
address from kfence pool.

Let's add a testcase to cover this case.

Link: https://lkml.kernel.org/r/210e561f7845697a32de44b643393890f180069f.1729272697.git.ritesh.list@gmail.com
Signed-off-by: Nirjhar Roy <nirjhar@linux.ibm.com>
Co-developed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Tested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Nirjhar Roy 2024-10-18 23:16:01 +05:30 committed by Andrew Morton
parent f364cdeb38
commit 811808d365
1 changed files with 17 additions and 0 deletions
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17
mm/kfence/kfence_test.c
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@ -383,6 +383,22 @@ static void test_use_after_free_read(struct kunit *test)
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
static void test_use_after_free_read_nofault(struct kunit *test)
{
const size_t size = 32;
char *addr;
char dst;
int ret;
setup_test_cache(test, size, 0, NULL);
addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
test_free(addr);
/* Use after free with *_nofault() */
ret = copy_from_kernel_nofault(&dst, addr, 1);
KUNIT_EXPECT_EQ(test, ret, -EFAULT);
KUNIT_EXPECT_FALSE(test, report_available());
}
static void test_double_free(struct kunit *test)
{
const size_t size = 32;
@ -780,6 +796,7 @@ static struct kunit_case kfence_test_cases[] = {
KFENCE_KUNIT_CASE(test_out_of_bounds_read),
KFENCE_KUNIT_CASE(test_out_of_bounds_write),
KFENCE_KUNIT_CASE(test_use_after_free_read),
KFENCE_KUNIT_CASE(test_use_after_free_read_nofault),
KFENCE_KUNIT_CASE(test_double_free),
KFENCE_KUNIT_CASE(test_invalid_addr_free),
KFENCE_KUNIT_CASE(test_corruption),