netdev - [PATCH net] net: tun: unlink NAPI from device on destruction

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Date:   Wed, 22 Jun 2022 21:20:39 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net, edumazet@...gle.com
Cc:     netdev@...r.kernel.org, pabeni@...hat.com,
        Jakub Kicinski <kuba@...nel.org>,
        syzbot+b75c138e9286ac742647@...kaller.appspotmail.com,
        peterpenkov96@...il.com, maheshb@...gle.com
Subject: [PATCH net] 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@...kaller.appspotmail.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: peterpenkov96@...il.com
CC: maheshb@...gle.com
---
 drivers/net/tun.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 87a635aac008..7fd0288c3789 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);
-- 
2.36.1