From: Steffen Klassert Subject: [PATCH 05/11] xfrm: fix rcu usage in xfrm_get_type_offload Date: Thu, 11 Jan 2018 12:37:40 +0100 Message-ID: <20180111113746.28186-6-steffen.klassert@secunet.com> References: <20180111113746.28186-1-steffen.klassert@secunet.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Herbert Xu , Steffen Klassert , To: David Miller Return-path: Received: from a.mx.secunet.com ([62.96.220.36]:50896 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933897AbeAKLhz (ORCPT ); Thu, 11 Jan 2018 06:37:55 -0500 In-Reply-To: <20180111113746.28186-1-steffen.klassert@secunet.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Sabrina Dubroca request_module can sleep, thus we cannot hold rcu_read_lock() while calling it. The function also jumps back and takes rcu_read_lock() again (in xfrm_state_get_afinfo()), resulting in an imbalance. This codepath is triggered whenever a new offloaded state is created. Fixes: ffdb5211da1c ("xfrm: Auto-load xfrm offload modules") Reported-by: syzbot+ca425f44816d749e8eb49755567a75ee48cf4a30@syzkaller.appspotmail.com Signed-off-by: Sabrina Dubroca Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_state.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 1e80f68e2266..429957412633 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -313,13 +313,14 @@ xfrm_get_type_offload(u8 proto, unsigned short family, bool try_load) if ((type && !try_module_get(type->owner))) type = NULL; + rcu_read_unlock(); + if (!type && try_load) { request_module("xfrm-offload-%d-%d", family, proto); try_load = 0; goto retry; } - rcu_read_unlock(); return type; } -- 2.14.1