| From ff1fa2081d173b01cebe2fbf0a2d0f1cee9ce4b5 Mon Sep 17 00:00:00 2001 |
| From: Jakub Kicinski <kuba@kernel.org> |
| Date: Wed, 29 Jun 2022 11:19:10 -0700 |
| Subject: net: tun: avoid disabling NAPI twice |
| |
| 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 |
| @@ -646,7 +646,8 @@ 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); |
| } |
| |