The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a8fc8cb5692aebb9c6f7afd4265366d25dcd1d01 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski kuba@kernel.org Date: Wed, 22 Jun 2022 21:21:05 -0700 Subject: [PATCH] net: tun: stop NAPI when detaching queues

While looking at a syzbot report I noticed the NAPI only gets disabled before it's deleted. I think that user can detach the queue before destroying the device and the NAPI will never be stopped.

Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver") Acked-by: Petar Penkov ppenkov@aviatrix.com Link: https://lore.kernel.org/r/20220623042105.2274812-1-kuba@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 7fd0288c3789..e2eb35887394 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -273,6 +273,12 @@ static void tun_napi_init(struct tun_struct *tun, struct tun_file *tfile, } }

+static void tun_napi_enable(struct tun_file *tfile) +{ + if (tfile->napi_enabled) + napi_enable(&tfile->napi); +} + static void tun_napi_disable(struct tun_file *tfile) { if (tfile->napi_enabled) @@ -653,8 +659,10 @@ static void __tun_detach(struct tun_file *tfile, bool clean) if (clean) { RCU_INIT_POINTER(tfile->tun, NULL); sock_put(&tfile->sk); - } else + } else { tun_disable_queue(tun, tfile); + tun_napi_disable(tfile); + }

synchronize_net(); tun_flow_delete_by_queue(tun, tun->numqueues + 1); @@ -808,6 +816,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file,

if (tfile->detached) { tun_enable_queue(tfile); + tun_napi_enable(tfile); } else { sock_hold(&tfile->sk); tun_napi_init(tun, tfile, napi, napi_frags);