From c1a279d79e313bd9b0ed31025edc68394bfc40ab Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sun, 22 Jan 2023 10:24:20 -0700 Subject: [PATCH] io_uring: fix double poll leak on repolling commit c0737fa9a5a5cf5a053bcc983f72d58919b997c6 upstream. We have re-polling for partial IO, so a request can be polled twice. If it used two poll entries the first time then on the second io_arm_poll_handler() it will find the old apoll entry and NULL kmalloc()'ed second entry, i.e. apoll->double_poll, so leaking it. Fixes: 10c873334feba ("io_uring: allow re-poll if we made progress") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/fee2452494222ecc7f1f88c8fb659baef971414a.1655852245.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 6852878e7762..eb7e3aa85fa3 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -5751,10 +5751,12 @@ static int io_arm_poll_handler(struct io_kiocb *req) mask |= POLLOUT | POLLWRNORM; } - if (req->flags & REQ_F_POLLED) + if (req->flags & REQ_F_POLLED) { apoll = req->apoll; - else + kfree(apoll->double_poll); + } else { apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC); + } if (unlikely(!apoll)) return IO_APOLL_ABORTED; apoll->double_poll = NULL;