linux-kernel - [PATCH] io_uring/msg_ring: reuse ctx->submitter_task read using READ

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Date: Fri, 26 Apr 2024 11:24:37 +0800
From: linke li <lilinke99@...com>
To: 
Cc: xujianhao01@...il.com,
	linke li <lilinke99@...com>,
	Jens Axboe <axboe@...nel.dk>,
	Pavel Begunkov <asml.silence@...il.com>,
	io-uring@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] io_uring/msg_ring: reuse ctx->submitter_task read using READ_ONCE instead of re-reading it

In io_msg_exec_remote(), ctx->submitter_task is read using READ_ONCE at
the beginning of the function, checked, and then re-read from
ctx->submitter_task, voiding all guarantees of the checks. Reuse the value
that was read by READ_ONCE to ensure the consistency of the task struct
throughout the function.

Signed-off-by: linke li <lilinke99@...com>
---
 io_uring/msg_ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index cd6dcf634ba3..d74670b39ed6 100644
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -83,7 +83,7 @@ static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func)
 		return -EOWNERDEAD;
 
 	init_task_work(&msg->tw, func);
-	if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL))
+	if (task_work_add(task, &msg->tw, TWA_SIGNAL))
 		return -EOWNERDEAD;
 
 	return IOU_ISSUE_SKIP_COMPLETE;
-- 
2.39.3 (Apple Git-146)