kunit: debugfs: Handle errors from alloc_string_stream()

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()

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")
Reviewed-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c
index 5bfc18ad5fffdc2c45557ecce4fa08add50935f7..382706dfb47d9dce30063a09140e95b23c8a0fda 100644 (file)
--- a/lib/kunit/debugfs.c
+++ b/lib/kunit/debugfs.c
@@ -111,14 +111,28 @@ 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.
+        */
+       stream = alloc_string_stream(GFP_KERNEL);
+       if (IS_ERR_OR_NULL(stream))
+               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);
@@ -126,6 +140,12 @@ 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)