We already store the `struct kunit *test` in the string_stream object itself, so we need don't need to store a copy of this pointer in every fragment in the stream.

Drop it, getting string_stream_fragment down the bare minimum: a list_head and the `char *` with the actual fragment.

Signed-off-by: Daniel Latypov dlatypov@google.com Reviewed-by: David Gow davidgow@google.com --- v1 -> v2: no changes --- lib/kunit/string-stream.c | 10 +++++----- lib/kunit/string-stream.h | 1 - 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c index a2496abef152..f5ae79c37400 100644 --- a/lib/kunit/string-stream.c +++ b/lib/kunit/string-stream.c @@ -22,7 +22,6 @@ static struct string_stream_fragment *alloc_string_stream_fragment( if (!frag) return ERR_PTR(-ENOMEM);

- frag->test = test; frag->fragment = kunit_kmalloc(test, len, gfp); if (!frag->fragment) return ERR_PTR(-ENOMEM); @@ -30,11 +29,12 @@ static struct string_stream_fragment *alloc_string_stream_fragment( return frag; }

-static void string_stream_fragment_destroy(struct string_stream_fragment *frag) +static void string_stream_fragment_destroy(struct kunit *test, + struct string_stream_fragment *frag) { list_del(&frag->node); - kunit_kfree(frag->test, frag->fragment); - kunit_kfree(frag->test, frag); + kunit_kfree(test, frag->fragment); + kunit_kfree(test, frag); }

int string_stream_vadd(struct string_stream *stream, @@ -89,7 +89,7 @@ static void string_stream_clear(struct string_stream *stream) frag_container_safe, &stream->fragments, node) { - string_stream_fragment_destroy(frag_container); + string_stream_fragment_destroy(stream->test, frag_container); } stream->length = 0; spin_unlock(&stream->lock); diff --git a/lib/kunit/string-stream.h b/lib/kunit/string-stream.h index 494dee0f24bd..b669f9a75a94 100644 --- a/lib/kunit/string-stream.h +++ b/lib/kunit/string-stream.h @@ -14,7 +14,6 @@ #include <linux/stdarg.h>

struct string_stream_fragment { - struct kunit *test; struct list_head node; char *fragment; };

kunit_kfree() exists to clean up allocations from kunit_kmalloc() and friends early instead of waiting for this to happen automatically at the end of the test.

But it can be used on *anything* registered with the kunit resource API.

E.g. the last 2 statements are equivalent: struct kunit_resource *res = something(); kfree(res->data); kunit_put_resource(res);

The problem is that there could be multiple resources that point to the same `data`.

E.g. you can have a named resource acting as a pseudo-global variable in a test. If you point it to data allocated with kunit_kmalloc(), then calling `kunit_kfree(ptr)` has the chance to delete either the named resource or to kfree `ptr`. Which one it does depends on the order the resources are registered as kunit_kfree() will delete resources in LIFO order.

So this patch restricts kunit_kfree() to only working on resources created by kunit_kmalloc(). Calling it is therefore guaranteed to free the memory, not do anything else.

Note: kunit_resource_instance_match() wasn't used outside of KUnit, so it should be safe to remove from the public interface. It's also generally dangerous, as shown above, and shouldn't be used.

Signed-off-by: Daniel Latypov dlatypov@google.com Reviewed-by: David Gow davidgow@google.com --- v1 -> v2: no changes --- include/kunit/resource.h | 16 ---------------- lib/kunit/kunit-test.c | 7 +++++++ lib/kunit/test.c | 10 ++++++++-- 3 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/include/kunit/resource.h b/include/kunit/resource.h index 09c2b34d1c61..cf6fb8f2ac1b 100644 --- a/include/kunit/resource.h +++ b/include/kunit/resource.h @@ -300,22 +300,6 @@ typedef bool (*kunit_resource_match_t)(struct kunit *test, struct kunit_resource *res, void *match_data);

-/** - * kunit_resource_instance_match() - Match a resource with the same instance. - * @test: Test case to which the resource belongs. - * @res: The resource. - * @match_data: The resource pointer to match against. - * - * An instance of kunit_resource_match_t that matches a resource whose - * allocation matches @match_data. - */ -static inline bool kunit_resource_instance_match(struct kunit *test, - struct kunit_resource *res, - void *match_data) -{ - return res->data == match_data; -} - /** * kunit_resource_name_match() - Match a resource with the same name. * @test: Test case to which the resource belongs. diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c index 13d0bd8b07a9..4df0335d0d06 100644 --- a/lib/kunit/kunit-test.c +++ b/lib/kunit/kunit-test.c @@ -161,6 +161,13 @@ static void kunit_resource_test_alloc_resource(struct kunit *test) kunit_put_resource(res); }

+static inline bool kunit_resource_instance_match(struct kunit *test, + struct kunit_resource *res, + void *match_data) +{ + return res->data == match_data; +} + /* * Note: tests below use kunit_alloc_and_get_resource(), so as a consequence * they have a reference to the associated resource that they must release diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 0fb2771ca03e..82019a78462e 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -689,12 +689,18 @@ void *kunit_kmalloc_array(struct kunit *test, size_t n, size_t size, gfp_t gfp) } EXPORT_SYMBOL_GPL(kunit_kmalloc_array);

+static inline bool kunit_kfree_match(struct kunit *test, + struct kunit_resource *res, void *match_data) +{ + /* Only match resources allocated with kunit_kmalloc() and friends. */ + return res->free == kunit_kmalloc_array_free && res->data == match_data; +} + void kunit_kfree(struct kunit *test, const void *ptr) { struct kunit_resource *res;

- res = kunit_find_resource(test, kunit_resource_instance_match, - (void *)ptr); + res = kunit_find_resource(test, kunit_kfree_match, (void *)ptr);

/* * Removing the resource from the list of resources drops the

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 --- v1 -> v2: fix typo in commit desc. --- lib/kunit/test.c | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 82019a78462e..c7ca87484968 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -698,18 +698,8 @@ static inline bool kunit_kfree_match(struct kunit *test,

void kunit_kfree(struct kunit *test, const void *ptr) { - struct kunit_resource *res; - - res = kunit_find_resource(test, kunit_kfree_match, (void *)ptr); - - /* - * Removing the resource from the list of resources drops the - * reference count to 1; the final put will trigger the free. - */ - kunit_remove_resource(test, res); - - kunit_put_resource(res); - + if (kunit_destroy_resource(test, kunit_kfree_match, (void *)ptr)) + KUNIT_FAIL(test, "kunit_kfree: %px already freed or not allocated by kunit", ptr); } EXPORT_SYMBOL_GPL(kunit_kfree);

The real kfree() function will silently return when given a NULL. So a user might reasonably think they can write the following code: char *buffer = NULL; if (param->use_buffer) buffer = kunit_kzalloc(test, 10, GFP_KERNEL); ... kunit_kfree(test, buffer);

As-is, kunit_kfree() will mark the test as FAILED when buffer is NULL. (And in earlier times, it would segfault).

Let's match the semantics of kfree().

Suggested-by: David Gow davidgow@google.com Signed-off-by: Daniel Latypov dlatypov@google.com --- v1 -> v2: add this patch to the series. --- lib/kunit/test.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index c7ca87484968..879c8db36cb5 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -698,6 +698,9 @@ static inline bool kunit_kfree_match(struct kunit *test,

void kunit_kfree(struct kunit *test, const void *ptr) { + if (!ptr) + return; + if (kunit_destroy_resource(test, kunit_kfree_match, (void *)ptr)) KUNIT_FAIL(test, "kunit_kfree: %px already freed or not allocated by kunit", ptr); }