From a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 8 Jan 2025 10:28:05 -0700 Subject: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period 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 Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/eventfd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'io_uring') diff --git a/io_uring/eventfd.c b/io_uring/eventfd.c index e37fddd5d9ce..ffc4bd17d078 100644 --- a/io_uring/eventfd.c +++ b/io_uring/eventfd.c @@ -38,7 +38,7 @@ static void io_eventfd_do_signal(struct rcu_head *rcu) 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) -- cgit v1.2.3