linux-kernel - [PATCH 5.10 005/105] io_uring: Use original task for req identity in io_identity

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Date:   Wed, 27 Jul 2022 18:09:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, lee@...nel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        io-uring@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 5.10 005/105] io_uring: Use original task for req identity in io_identity_cow()

From: Lee Jones <lee@...nel.org>

This issue is conceptually identical to the one fixed in 29f077d07051
("io_uring: always use original task when preparing req identity"), so
rather than reinvent the wheel, I'm shamelessly quoting the commit
message from that patch - thanks Jens:

 "If the ring is setup with IORING_SETUP_IOPOLL and we have more than
  one task doing submissions on a ring, we can up in a situation where
  we assign the context from the current task rather than the request
  originator.

  Always use req->task rather than assume it's the same as current.

  No upstream patch exists for this issue, as only older kernels with
  the non-native workers have this problem."

Cc: Jens Axboe <axboe@...nel.dk>
Cc: Pavel Begunkov <asml.silence@...il.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: io-uring@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org
Fixes: 5c3462cfd123b ("io_uring: store io_identity in io_uring_task")
Signed-off-by: Lee Jones <lee@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/io_uring.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1325,7 +1325,7 @@ static void io_req_clean_work(struct io_
  */
 static bool io_identity_cow(struct io_kiocb *req)
 {
-	struct io_uring_task *tctx = current->io_uring;
+	struct io_uring_task *tctx = req->task->io_uring;
 	const struct cred *creds = NULL;
 	struct io_identity *id;