2021-09-09 12:10:32

by Zhang, Qiang

Subject: [PATCH] io-wq: fix memory leak in create_io_worker()

From: "Qiang.zhang" <[email protected]>

BUG: memory leak
unreferenced object 0xffff888126fcd6c0 (size 192):
comm "syz-executor.1", pid 11934, jiffies 4294983026 (age 15.690s)
backtrace:
[<ffffffff81632c91>] kmalloc_node include/linux/slab.h:609 [inline]
[<ffffffff81632c91>] kzalloc_node include/linux/slab.h:732 [inline]
[<ffffffff81632c91>] create_io_worker+0x41/0x1e0 fs/io-wq.c:739
[<ffffffff8163311e>] io_wqe_create_worker fs/io-wq.c:267 [inline]
[<ffffffff8163311e>] io_wqe_enqueue+0x1fe/0x330 fs/io-wq.c:866
[<ffffffff81620b64>] io_queue_async_work+0xc4/0x200 fs/io_uring.c:1473
[<ffffffff8162c59c>] __io_queue_sqe+0x34c/0x510 fs/io_uring.c:6933
[<ffffffff8162c7ab>] io_req_task_submit+0x4b/0xa0 fs/io_uring.c:2233
[<ffffffff8162cb48>] io_async_task_func+0x108/0x1c0 fs/io_uring.c:5462
[<ffffffff816259e3>] tctx_task_work+0x1b3/0x3a0 fs/io_uring.c:2158
[<ffffffff81269b43>] task_work_run+0x73/0xb0 kernel/task_work.c:164
[<ffffffff812dcdd1>] tracehook_notify_signal include/linux/tracehook.h:212 [inline]
[<ffffffff812dcdd1>] handle_signal_work kernel/entry/common.c:146 [inline]
[<ffffffff812dcdd1>] exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
[<ffffffff812dcdd1>] exit_to_user_mode_prepare+0x151/0x180 kernel/entry/common.c:209
[<ffffffff843ff25d>] __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
[<ffffffff843ff25d>] syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:302
[<ffffffff843fa4a2>] do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
[<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

when create_io_thread() return error, and not retry, the worker object
need to be freed.

Reported-by: [email protected]
Signed-off-by: Qiang.zhang <[email protected]>
---
fs/io-wq.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 35e7ee26f7ea..27fa0506c1a6 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -709,6 +709,7 @@ static void create_worker_cont(struct callback_head *cb)
}
raw_spin_unlock(&wqe->lock);
io_worker_ref_put(wqe->wq);
+ kfree(worker);
return;
}

@@ -725,6 +726,7 @@ static void io_workqueue_create(struct work_struct *work)
if (!io_queue_worker_create(worker, acct, create_worker_cont)) {
clear_bit_unlock(0, &worker->create_state);
io_worker_release(worker);
+ kfree(worker);
}
}

@@ -759,6 +761,7 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
if (!IS_ERR(tsk)) {
io_init_new_worker(wqe, worker, tsk);
} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
+ kfree(worker);
goto fail;
} else {
INIT_WORK(&worker->work, io_workqueue_create);
--
2.25.1

2021-09-09 14:26:43

by Jens Axboe

Subject: Re: [PATCH] io-wq: fix memory leak in create_io_worker()

On 9/9/21 5:58 AM, [email protected] wrote:
> From: "Qiang.zhang" <[email protected]>
>
> BUG: memory leak
> unreferenced object 0xffff888126fcd6c0 (size 192):
> comm "syz-executor.1", pid 11934, jiffies 4294983026 (age 15.690s)
> backtrace:
> [<ffffffff81632c91>] kmalloc_node include/linux/slab.h:609 [inline]
> [<ffffffff81632c91>] kzalloc_node include/linux/slab.h:732 [inline]
> [<ffffffff81632c91>] create_io_worker+0x41/0x1e0 fs/io-wq.c:739
> [<ffffffff8163311e>] io_wqe_create_worker fs/io-wq.c:267 [inline]
> [<ffffffff8163311e>] io_wqe_enqueue+0x1fe/0x330 fs/io-wq.c:866
> [<ffffffff81620b64>] io_queue_async_work+0xc4/0x200 fs/io_uring.c:1473
> [<ffffffff8162c59c>] __io_queue_sqe+0x34c/0x510 fs/io_uring.c:6933
> [<ffffffff8162c7ab>] io_req_task_submit+0x4b/0xa0 fs/io_uring.c:2233
> [<ffffffff8162cb48>] io_async_task_func+0x108/0x1c0 fs/io_uring.c:5462
> [<ffffffff816259e3>] tctx_task_work+0x1b3/0x3a0 fs/io_uring.c:2158
> [<ffffffff81269b43>] task_work_run+0x73/0xb0 kernel/task_work.c:164
> [<ffffffff812dcdd1>] tracehook_notify_signal include/linux/tracehook.h:212 [inline]
> [<ffffffff812dcdd1>] handle_signal_work kernel/entry/common.c:146 [inline]
> [<ffffffff812dcdd1>] exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
> [<ffffffff812dcdd1>] exit_to_user_mode_prepare+0x151/0x180 kernel/entry/common.c:209
> [<ffffffff843ff25d>] __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
> [<ffffffff843ff25d>] syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:302
> [<ffffffff843fa4a2>] do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
> [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> when create_io_thread() return error, and not retry, the worker object
> need to be freed.

Thanks, this one looks complete.

--
Jens Axboe