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linux/debian/patches/patchset-pf/steady/0096-io_uring-futex-ensure-io_futex_wait-cleans-up-proper.patch

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From 2988d1717679b28423a316a92aaa7cae7fddceab Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 21 Aug 2025 13:23:21 -0600
Subject: io_uring/futex: ensure io_futex_wait() cleans up properly on failure
The io_futex_data is allocated upfront and assigned to the io_kiocb
async_data field, but the request isn't marked with REQ_F_ASYNC_DATA
at that point. Those two should always go together, as the flag tells
io_uring whether the field is valid or not.
Additionally, on failure cleanup, the futex handler frees the data but
does not clear ->async_data. Clear the data and the flag in the error
path as well.
Thanks to Trend Micro Zero Day Initiative and particularly ReDress for
reporting this.
Cc: stable@vger.kernel.org
Fixes: 194bb58c6090 ("io_uring: add support for futex wake and wait")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/futex.c | 3 +++
1 file changed, 3 insertions(+)
--- a/io_uring/futex.c
+++ b/io_uring/futex.c
@@ -288,6 +288,7 @@ int io_futex_wait(struct io_kiocb *req,
goto done_unlock;
}
+ req->flags |= REQ_F_ASYNC_DATA;
req->async_data = ifd;
ifd->q = futex_q_init;
ifd->q.bitset = iof->futex_mask;
@@ -309,6 +310,8 @@ done:
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
+ req->async_data = NULL;
+ req->flags &= ~REQ_F_ASYNC_DATA;
kfree(ifd);
return IOU_COMPLETE;
}