From: Jakub Kicinski kuba@kernel.org
commit ff1fa2081d173b01cebe2fbf0a2d0f1cee9ce4b5 upstream.
Eric reports that syzbot made short work out of my speculative fix. Indeed when queue gets detached its tfile->tun remains, so we would try to stop NAPI twice with a detach(), close() sequence.
Alternative fix would be to move tun_napi_disable() to tun_detach_all() and let the NAPI run after the queue has been detached.
Fixes: a8fc8cb5692a ("net: tun: stop NAPI when detaching queues") Reported-by: syzbot syzkaller@googlegroups.com Reported-by: Eric Dumazet edumazet@google.com Reviewed-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20220629181911.372047-1-kuba@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/tun.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -696,7 +696,8 @@ static void __tun_detach(struct tun_file tun = rtnl_dereference(tfile->tun);
if (tun && clean) { - tun_napi_disable(tfile); + if (!tfile->detached) + tun_napi_disable(tfile); tun_napi_del(tfile); }