Re: [PATCH v2 RESEND] kunit: debugfs: Handle errors from alloc_string_stream()

On Mon, Oct 30, 2023 at 6:47 AM Richard Fitzgerald rf@opensource.cirrus.com wrote:

In kunit_debugfs_create_suite() give up and skip creating the debugfs file if any of the alloc_string_stream() calls return an error or NULL. Only put a value in the log pointer of kunit_suite and kunit_test if it is a valid pointer to a log.

This prevents the potential invalid dereference reported by smatch:

lib/kunit/debugfs.c:115 kunit_debugfs_create_suite() error: 'suite->log' dereferencing possible ERR_PTR() lib/kunit/debugfs.c:119 kunit_debugfs_create_suite() error: 'test_case->log' dereferencing possible ERR_PTR()

Hello!

Thanks for sending the re-sends of these patches! This patch also looks good to me! I have one comment below but I would still be happy with the patch as is.

Reviewed-by: Rae Moar rmoar@google.com

Thanks! -Rae

Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com Reported-by: Dan Carpenter dan.carpenter@linaro.org Fixes: 05e2006ce493 ("kunit: Use string_stream for test log")

---

lib/kunit/debugfs.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c index 270d185737e6..9d167adfa746 100644 --- a/lib/kunit/debugfs.c +++ b/lib/kunit/debugfs.c @@ -109,14 +109,28 @@ static const struct file_operations debugfs_results_fops = { void kunit_debugfs_create_suite(struct kunit_suite *suite) { struct kunit_case *test_case;

•   struct string_stream *stream;
  
  

•   /* Allocate logs before creating debugfs representation. */
  

•   suite->log = alloc_string_stream(GFP_KERNEL);
  

•   string_stream_set_append_newlines(suite->log, true);
  

•   /*
  

•    * Allocate logs before creating debugfs representation.
  

•    * The suite->log and test_case->log pointer are expected to be NULL
  

•    * if there isn't a log, so only set it if the log stream was created
  

•    * successfully.
  

•    */
  

I like this new comment. Thanks!

•   stream = alloc_string_stream(GFP_KERNEL);
  

•   if (IS_ERR_OR_NULL(stream))
  

In response to Dan Carpenter's comment from the last version, I see the benefits of changing IS_ERR_OR_NULL() to IS_ERR() instead because "stream" will not be NULL. This would then also be the same as the check in kunit_alloc_string_stream.

However, I also see the benefit of checking for NULL just in case anyways.

I'm overall happy with either solution but just wanted to bring this up.

•           return;
  

•   string_stream_set_append_newlines(stream, true);
  

•   suite->log = stream;
  
    kunit_suite_for_each_test_case(suite, test_case) {
  

•           test_case->log = alloc_string_stream(GFP_KERNEL);
  

•           string_stream_set_append_newlines(test_case->log, true);
  

•           stream = alloc_string_stream(GFP_KERNEL);
  

•           if (IS_ERR_OR_NULL(stream))
  

•                   goto err;
  

•           string_stream_set_append_newlines(stream, true);
  

•           test_case->log = stream;
    }
  
    suite->debugfs = debugfs_create_dir(suite->name, debugfs_rootdir);
  

@@ -124,6 +138,12 @@ void kunit_debugfs_create_suite(struct kunit_suite *suite) debugfs_create_file(KUNIT_DEBUGFS_RESULTS, S_IFREG | 0444, suite->debugfs, suite, &debugfs_results_fops);

•   return;
  

+err:

•   string_stream_destroy(suite->log);
  

•   kunit_suite_for_each_test_case(suite, test_case)
  

•           string_stream_destroy(test_case->log);
  

}

void kunit_debugfs_destroy_suite(struct kunit_suite *suite)

2.30.2