From c0737fa9a5a5cf5a053bcc983f72d58919b997c6 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed, 22 Jun 2022 00:00:37 +0100
Subject: [PATCH] io_uring: fix double poll leak on repolling
Git-commit: c0737fa9a5a5cf5a053bcc983f72d58919b997c6
Patch-mainline: v5.19-rc4
References: bsc#1205205

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 <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fee2452494222ecc7f1f88c8fb659baef971414a.1655852245.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
 fs/io_uring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index cb719a53b8bd..5c95755619e2 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7208,6 +7208,7 @@ static int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
 		mask |= EPOLLEXCLUSIVE;
 	if (req->flags & REQ_F_POLLED) {
 		apoll = req->apoll;
+		kfree(apoll->double_poll);
 	} else if (!(issue_flags & IO_URING_F_UNLOCKED) &&
 		   !list_empty(&ctx->apoll_cache)) {
 		apoll = list_first_entry(&ctx->apoll_cache, struct async_poll,
-- 
2.35.3