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 <brendanhiggins@xxxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Fixes: adf505457032 ("kunit: fix UAF when run kfence test case test_gfpzero")
Reviewed-by: David Gow <davidgow@xxxxxxxxxx>
Reviewed-by: Rae Moar <rmoar@xxxxxxxxxx>
Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240319104857.70783-3-mic@xxxxxxxxxxx
---
Changes since v2:
* Add Fixes tag as suggested by David.
* Add David's and Rae's Reviewed-by.
Changes since v1:
* Add Kees's Reviewed-by.
---
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
