6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe <axboe@xxxxxxxxx>
Commit c9a40292a44e78f71258b8522655bffaf5753bdb upstream.
io_eventfd_do_signal() is invoked from an RCU callback, but when
dropping the reference to the io_ev_fd, it calls io_eventfd_free()
directly if the refcount drops to zero. This isn't correct, as any
potential freeing of the io_ev_fd should be deferred another RCU grace
period.
Just call io_eventfd_put() rather than open-code the dec-and-test and
free, which will correctly defer it another RCU grace period.
Fixes: 21a091b970cd ("io_uring: signal registered eventfd to process deferred task work")
Reported-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/eventfd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/io_uring/eventfd.c
+++ b/io_uring/eventfd.c
@@ -38,7 +38,7 @@ static void io_eventfd_do_signal(struct
eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE);
if (refcount_dec_and_test(&ev_fd->refs))
- io_eventfd_free(rcu);
+ call_rcu(&ev_fd->rcu, io_eventfd_free);
}
void io_eventfd_signal(struct io_ring_ctx *ctx)
