Commit d05662e9 authored by John Stultz's avatar John Stultz Committed by Xie XiuQi
Browse files

locking/ww_mutex/test: Fix potential workqueue corruption 

stable inclusion
from stable-v5.10.202
commit 9ed2d68b3925145f5f51c46559484881d6082f75
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9RFIG
CVE: CVE-2023-52836

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9ed2d68b3925145f5f51c46559484881d6082f75



--------------------------------

[ Upstream commit bccdd808902f8c677317cec47c306e42b93b849e ]

In some cases running with the test-ww_mutex code, I was seeing
odd behavior where sometimes it seemed flush_workqueue was
returning before all the work threads were finished.

Often this would cause strange crashes as the mutexes would be
freed while they were being used.

Looking at the code, there is a lifetime problem as the
controlling thread that spawns the work allocates the
"struct stress" structures that are passed to the workqueue
threads. Then when the workqueue threads are finished,
they free the stress struct that was passed to them.

Unfortunately the workqueue work_struct node is in the stress
struct. Which means the work_struct is freed before the work
thread returns and while flush_workqueue is waiting.

It seems like a better idea to have the controlling thread
both allocate and free the stress structures, so that we can
be sure we don't corrupt the workqueue by freeing the structure
prematurely.

So this patch reworks the test to do so, and with this change
I no longer see the early flush_workqueue returns.

Signed-off-by: default avatarJohn Stultz <jstultz@google.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230922043616.19282-3-jstultz@google.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarsanglipeng <sanglipeng1@jd.com>
Signed-off-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
parent 5d32aa69

kernel/locking/test-ww_mutex.c

+12 −8
Original line number Diff line number Diff line
@@ -426,7 +426,6 @@ static void stress_inorder_work(struct work_struct *work) 
	} while (!time_after(jiffies, stress->timeout));



	kfree(order);

	kfree(stress);

}



struct reorder_lock {
@@ -491,7 +490,6 @@ static void stress_reorder_work(struct work_struct *work) 
	list_for_each_entry_safe(ll, ln, &locks, link)

		kfree(ll);

	kfree(order);

	kfree(stress);

}



static void stress_one_work(struct work_struct *work)
@@ -512,8 +510,6 @@ static void stress_one_work(struct work_struct *work) 
			break;

		}

	} while (!time_after(jiffies, stress->timeout));



	kfree(stress);

}



#define STRESS_INORDER BIT(0)
@@ -524,15 +520,24 @@ static void stress_one_work(struct work_struct *work) 
static int stress(int nlocks, int nthreads, unsigned int flags)

{

	struct ww_mutex *locks;

	int n;

	struct stress *stress_array;

	int n, count;



	locks = kmalloc_array(nlocks, sizeof(*locks), GFP_KERNEL);

	if (!locks)

		return -ENOMEM;



	stress_array = kmalloc_array(nthreads, sizeof(*stress_array),

				     GFP_KERNEL);

	if (!stress_array) {

		kfree(locks);

		return -ENOMEM;

	}



	for (n = 0; n < nlocks; n++)

		ww_mutex_init(&locks[n], &ww_class);



	count = 0;

	for (n = 0; nthreads; n++) {

		struct stress *stress;

		void (*fn)(struct work_struct *work);
@@ -556,9 +561,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) 
		if (!fn)

			continue;



		stress = kmalloc(sizeof(*stress), GFP_KERNEL);

		if (!stress)

			break;

		stress = &stress_array[count++];



		INIT_WORK(&stress->work, fn);

		stress->locks = locks;
@@ -573,6 +576,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) 


	for (n = 0; n < nlocks; n++)

		ww_mutex_destroy(&locks[n]);

	kfree(stress_array);

	kfree(locks);



	return 0;