On Fri, Jul 22, 2022 at 1:15 PM Daniel Latypov dlatypov@google.com wrote:
kunit_kfree() can only work on data ("resources") allocated by KUnit.
Currently for code like this,
void *ptr = kmalloc(4, GFP_KERNEL); kunit_kfree(test, ptr);
kunit_kfree() will segfault.
It'll try and look up the kunit_resource associated with `ptr` and get a NULL back, but it won't check for this. This means we also segfault if you double-free.
Change kunit_kfree() so it'll notice these invalid pointers and respond by failing the test.
Implementation: kunit_destroy_resource() does what kunit_kfree() does, but is more generic and returns -ENOENT when it can't find the resource. Sadly, unlike just letting it crash, this means we don't get a stack trace. But kunit_kfree() is so infrequently used it shouldn't be hard to track down the bad callsite anyways.
After this change, the above code gives:
# example_simple_test: EXPECTATION FAILED at lib/kunit/test.c:702 kunit_kfree: 00000000626ec200 already freed or not allocated by kunit
Signed-off-by: Daniel Latypov dlatypov@google.com Reviewed-by: David Gow davidgow@google.com
Reviewed-by: Brendan Higgins brendanhiggins@google.com