6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
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@google.com Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)