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

Richard Fitzgerald
2023-10-30T10:47:56Z

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")
---
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.
+ */
+ 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);
@@ -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