linux-kernel - [PATCH 5.8 154/186] io_uring: set table->files[i] to NULL when io_sqe_file

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Date:   Tue,  8 Sep 2020 17:24:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiufei Xue <jiufei.xue@...ux.alibaba.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.8 154/186] io_uring: set table->files[i] to NULL when io_sqe_file_register failed

From: Jiufei Xue <jiufei.xue@...ux.alibaba.com>

commit 95d1c8e5f801e959a89181a2548a3efa60a1a6ce upstream.

While io_sqe_file_register() failed in __io_sqe_files_update(),
table->files[i] still point to the original file which may freed
soon, and that will trigger use-after-free problems.

Cc: stable@...r.kernel.org
Fixes: f3bd9dae3708 ("io_uring: fix memleak in __io_sqe_files_update()")
Signed-off-by: Jiufei Xue <jiufei.xue@...ux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/io_uring.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6957,6 +6957,7 @@ static int __io_sqe_files_update(struct
 			table->files[index] = file;
 			err = io_sqe_file_register(ctx, file, i);
 			if (err) {
+				table->files[index] = NULL;
 				fput(file);
 				break;
 			}