From: Jakub Kicinski <kuba@kernel.org>
Date: Thu, 23 Jun 2022 04:20:39 +0000 (-0700)
Subject: net: tun: unlink NAPI from device on destruction
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3b9bc84d311104906d2b4995a9a02d7b7ddab2db;p=linux.git

net: tun: unlink NAPI from device on destruction

Syzbot found a race between tun file and device destruction.
NAPIs live in struct tun_file which can get destroyed before
the netdev so we have to del them explicitly. The current
code is missing deleting the NAPI if the queue was detached
first.

Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
Reported-by: syzbot+b75c138e9286ac742647@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20220623042039.2274708-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 87a635aac0084..7fd0288c37898 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -727,6 +727,7 @@ static void tun_detach_all(struct net_device *dev)
 		sock_put(&tfile->sk);
 	}
 	list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
+		tun_napi_del(tfile);
 		tun_enable_queue(tfile);
 		tun_queue_purge(tfile);
 		xdp_rxq_info_unreg(&tfile->xdp_rxq);