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From: Stefan Metzmacher <[email protected]>
To: [email protected]
Cc: Stefan Metzmacher <[email protected]>
Subject: [RFC PATCH 06/10] io_uring: protect against future set_task_comm() overflows.
Date: Mon, 15 Mar 2021 18:01:44 +0100	[thread overview]
Message-ID: <6fc10a3a30de9173a50d608edb576de4dbed1864.1615826736.git.metze@samba.org> (raw)
In-Reply-To: <[email protected]>

Signed-off-by: Stefan Metzmacher <[email protected]>
---
 fs/io_uring.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e7e2d87cd9c1..e88d9f95d0aa 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7905,7 +7905,19 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
 			goto err_sqpoll;
 		}
 
-		sprintf(tsk_comm, "iou-sqp-%d", sqd->task_pid);
+		/*
+		 * The limit value of pid_max_max/PID_MAX_LIMIT
+		 * is 4 * 1024 * 1024 = 4194304.
+		 *
+		 * TASK_COMM_LEN is 16, so we have 15 chars to fill.
+		 *
+		 * With "iou-sqp-4194304" we just fit into 15 chars.
+		 * If that ever changes we may better add some special
+		 * handling for PF_IO_WORKER in proc_task_name(), as that
+		 * allows up to 63 chars.
+		 */
+		WARN_ON(snprintf(tsk_comm, sizeof(tsk_comm),
+				 "iou-sqp-%d", sqd->task_pid) >= sizeof(tsk_comm));
 		set_task_comm(tsk, tsk_comm);
 
 		if (sqd->sq_cpu != -1)
-- 
2.25.1


  parent reply	other threads:[~2021-03-15 17:04 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-19 23:27 Problems with io_threads Stefan Metzmacher
2021-03-15 17:01 ` [RFC PATCH 00/10] Complete setup before calling wake_up_new_task() and improve task->comm Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 01/10] kernel: always initialize task->pf_io_worker to NULL Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 02/10] io_uring: io_sq_thread() no longer needs to reset current->pf_io_worker Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 03/10] io-wq: call set_task_comm() before wake_up_new_task() Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 04/10] io_uring: complete sq_thread setup before calling wake_up_new_task() Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 05/10] io-wq: protect against future set_task_comm() overflows Stefan Metzmacher
2021-03-15 17:01   ` Stefan Metzmacher [this message]
2021-03-15 17:01   ` [RFC PATCH 07/10] fs/proc: hide PF_IO_WORKER in get_task_cmdline() Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 08/10] fs/proc: protect /proc/<pid>/[task/<tid>]/comm for PF_IO_WORKER Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 09/10] io-wq: add io_wq_worker_comm() helper function for dynamic proc_task_comm() generation Stefan Metzmacher
2021-03-15 17:01   ` [RFC PATCH 10/10] fs/proc: make use of io_wq_worker_comm() for PF_IO_WORKER threads Stefan Metzmacher
2021-03-17 22:42   ` [RFC PATCH 00/10] Complete setup before calling wake_up_new_task() and improve task->comm Jens Axboe
2021-03-17 23:06     ` Stefan Metzmacher
2021-03-17 23:26       ` Jens Axboe
2021-03-20  0:00   ` [PATCH v2 0/5] " Stefan Metzmacher
2021-03-20  0:00     ` [PATCH v2 1/5] kernel: always initialize task->pf_io_worker to NULL Stefan Metzmacher
2021-03-20  0:00     ` [PATCH v2 2/5] io_uring: io_sq_thread() no longer needs to reset current->pf_io_worker Stefan Metzmacher
2021-03-20  0:00     ` [PATCH v2 3/5] io-wq: call set_task_comm() before wake_up_new_task() Stefan Metzmacher
2021-03-20  0:00     ` [PATCH v2 4/5] io_uring: complete sq_thread setup before calling wake_up_new_task() Stefan Metzmacher
2021-03-20  0:00     ` [PATCH v2 5/5] fs/proc: hide PF_IO_WORKER in get_task_cmdline() Stefan Metzmacher
2021-03-20  1:24     ` [PATCH v2 0/5] Complete setup before calling wake_up_new_task() and improve task->comm Jens Axboe
2021-03-20 19:22       ` Stefan Metzmacher
2021-03-20 22:39         ` Jens Axboe
2021-03-19 23:46 ` Problems with io_threads Jens Axboe
2021-03-20  0:25   ` Stefan Metzmacher
2021-03-20  1:20     ` Jens Axboe

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