linux-kernel - [PATCH 5.15 221/277] io_uring: fix race between timeout flush and removal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220412062948.440027567@linuxfoundation.org>
Date:   Tue, 12 Apr 2022 08:30:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.15 221/277] io_uring: fix race between timeout flush and removal

From: Jens Axboe <axboe@...nel.dk>

commit e677edbcabee849bfdd43f1602bccbecf736a646 upstream.

io_flush_timeouts() assumes the timeout isn't in progress of triggering
or being removed/canceled, so it unconditionally removes it from the
timeout list and attempts to cancel it.

Leave it on the list and let the normal timeout cancelation take care
of it.

Cc: stable@...r.kernel.org # 5.5+
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/io_uring.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1538,12 +1538,11 @@ static void io_flush_timeouts(struct io_
 	__must_hold(&ctx->completion_lock)
 {
 	u32 seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
+	struct io_kiocb *req, *tmp;
 
 	spin_lock_irq(&ctx->timeout_lock);
-	while (!list_empty(&ctx->timeout_list)) {
+	list_for_each_entry_safe(req, tmp, &ctx->timeout_list, timeout.list) {
 		u32 events_needed, events_got;
-		struct io_kiocb *req = list_first_entry(&ctx->timeout_list,
-						struct io_kiocb, timeout.list);
 
 		if (io_is_timeout_noseq(req))
 			break;
@@ -1560,7 +1559,6 @@ static void io_flush_timeouts(struct io_
 		if (events_got < events_needed)
 			break;
 
-		list_del_init(&req->timeout.list);
 		io_kill_timeout(req, 0);
 	}
 	ctx->cq_last_tm_flush = seq;
@@ -6205,6 +6203,7 @@ static int io_timeout_prep(struct io_kio
 	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
 		return -EFAULT;
 
+	INIT_LIST_HEAD(&req->timeout.list);
 	data->mode = io_translate_timeout_mode(flags);
 	hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);