On Sat, Oct 2, 2021 at 9:36 AM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote:
>
> When a user filters by a suite and not a test, e.g.
> $ ./tools/testing/kunit/kunit.py run 'suite_name'
>
> it hits this code
> const int len = strlen(filter_glob);
> ...
> parsed->suite_glob = kmalloc(len, GFP_KERNEL);
> which fails to allocate space for the terminating NULL.
>
> Somehow, it seems like we can't easily reproduce this under UML, so the
> existing `parse_filter_test()` didn't catch this.
>
> Fix this by allocating `len + 1` and switch to kzalloc() just to be a
> bit more defensive. We're only going to run this code once per kernel
> boot, and it should never be very long.
>
> Also update the unit tests to be a bit more cautious.
> This bug showed up as a NULL pointer dereference here:
> > KUNIT_EXPECT_STREQ(test, (const char *)filtered.start[0][0]->name, "suite0");
> `filtered.start[0][0]` was NULL, and `name` is at offset 0 in the struct,
> so `...->name` was also NULL.
>
> Fixes: 3b29021ddd10 ("kunit: tool: allow filtering test cases via glob")
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Signed-off-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
> ---
Nice catch. I guess this is why we're all going to be switching to
rust one day. :-)
The fix looks good, and I ran it under KASAN just to be sure, and it passed.
Reviewed-by: David Gow <davidgow@xxxxxxxxxx>
-- David
> lib/kunit/executor.c | 2 +-
> lib/kunit/executor_test.c | 1 +
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
> index bab3ab940acc..1d7fecd33261 100644
> --- a/lib/kunit/executor.c
> +++ b/lib/kunit/executor.c
> @@ -33,7 +33,7 @@ static void kunit_parse_filter_glob(struct kunit_test_filter *parsed,
> const char *period = strchr(filter_glob, '.');
>
> if (!period) {
> - parsed->suite_glob = kmalloc(len, GFP_KERNEL);
> + parsed->suite_glob = kzalloc(len + 1, GFP_KERNEL);
> parsed->test_glob = NULL;
> strcpy(parsed->suite_glob, filter_glob);
> return;
> diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
> index e6323f398dfa..7d2b8dc668b1 100644
> --- a/lib/kunit/executor_test.c
> +++ b/lib/kunit/executor_test.c
> @@ -149,6 +149,7 @@ static void filter_suites_test(struct kunit *test)
>
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start[0]);
> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start[0][0]);
> KUNIT_EXPECT_STREQ(test, (const char *)filtered.start[0][0]->name, "suite0");
> }
>
>
> base-commit: 3b29021ddd10cfb6b2565c623595bd3b02036f33
> --
> 2.33.0.800.g4c38ced690-goog
>
