2024-02-29 17:05:30

by Mickaël Salaün

Subject: [PATCH v1 3/8] kunit: Fix kthread reference

There is a race condition when a kthread finishes after the deadline and
before the call to kthread_stop(), which may lead to use after free.

Cc: Brendan Higgins <[email protected]>
Cc: David Gow <[email protected]>
Cc: Rae Moar <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
---
lib/kunit/try-catch.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index a5cb2ef70a25..73f5007f20ea 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -11,6 +11,7 @@
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
+#include <linux/sched/task.h>

#include "try-catch-impl.h"

@@ -65,14 +66,15 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
try_catch->context = context;
try_catch->try_completion = &try_completion;
try_catch->try_result = 0;
- task_struct = kthread_run(kunit_generic_run_threadfn_adapter,
- try_catch,
- "kunit_try_catch_thread");
+ task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
+ try_catch, "kunit_try_catch_thread");
if (IS_ERR(task_struct)) {
try_catch->try_result = PTR_ERR(task_struct);
try_catch->catch(try_catch->context);
return;
}
+ get_task_struct(task_struct);
+ wake_up_process(task_struct);

time_remaining = wait_for_completion_timeout(&try_completion,
kunit_test_timeout());
@@ -82,6 +84,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
kthread_stop(task_struct);
}

+ put_task_struct(task_struct);
exit_code = try_catch->try_result;

if (!exit_code)
--
2.44.0

2024-02-29 18:33:23

by Kees Cook

Subject: Re: [PATCH v1 3/8] kunit: Fix kthread reference

On Thu, Feb 29, 2024 at 06:04:04PM +0100, Micka?l Sala?n wrote:
> There is a race condition when a kthread finishes after the deadline and
> before the call to kthread_stop(), which may lead to use after free.
>
> Cc: Brendan Higgins <[email protected]>
> Cc: David Gow <[email protected]>
> Cc: Rae Moar <[email protected]>
> Cc: Shuah Khan <[email protected]>
> Signed-off-by: Micka?l Sala?n <[email protected]>

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook