[PATCH AUTOSEL 5.7 07/60] io_uring: fix req->work corruption

Sasha Levin
2020-08-10T19:29:49Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit 8ef77766ba8694968ed4ba24311b4bacee14f235 ]

req->work and req->task_work are in a union, so io_req_task_queue() screws
everything that was in work. De-union them for now.

[ 704.367253] BUG: unable to handle page fault for address:
ffffffffaf7330d0
[ 704.367256] #PF: supervisor write access in kernel mode
[ 704.367256] #PF: error_code(0x0003) - permissions violation
[ 704.367261] CPU: 6 PID: 1654 Comm: io_wqe_worker-0 Tainted: G
I 5.8.0-rc2-00038-ge28d0bdc4863-dirty #498
[ 704.367265] RIP: 0010:_raw_spin_lock+0x1e/0x36
...
[ 704.367276] __alloc_fd+0x35/0x150
[ 704.367279] __get_unused_fd_flags+0x25/0x30
[ 704.367280] io_openat2+0xcb/0x1b0
[ 704.367283] io_issue_sqe+0x36a/0x1320
[ 704.367294] io_wq_submit_work+0x58/0x160
[ 704.367295] io_worker_handle_work+0x2a3/0x430
[ 704.367296] io_wqe_worker+0x2a0/0x350
[ 704.367301] kthread+0x136/0x180
[ 704.367304] ret_from_fork+0x22/0x30

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4e09af1d5d223..80a612d1e12bb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -645,12 +645,12 @@ struct io_kiocb {
* restore the work, if needed.
*/
struct {
- struct callback_head task_work;
struct hlist_node hash_node;
struct async_poll *apoll;
};
struct io_wq_work work;
};
+ struct callback_head task_work;
};

#define IO_PLUG_THRESHOLD 2
--
2.25.1