[PATCH AUTOSEL 4.4 01/17] netfilter: nfnetlink: avoid deadlock due to synchronous request_module

[PATCH AUTOSEL 4.4 01/17] netfilter: nfnetlink: avoid deadlock due to synchronous request_module

[Sasha Levin]

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 1b0890cd60829bd51455dc5ad689ed58c4408227 ]

Thomas and Juliana report a deadlock when running:

(rmmod nf_conntrack_netlink/xfrm_user)

  conntrack -e NEW -E &
  modprobe -v xfrm_user

They provided following analysis:

conntrack -e NEW -E
    netlink_bind()
        netlink_lock_table() -> increases "nl_table_users"
            nfnetlink_bind()
            # does not unlock the table as it's locked by netlink_bind()
                __request_module()
                    call_usermodehelper_exec()

This triggers "modprobe nf_conntrack_netlink" from kernel, netlink_bind()
won't return until modprobe process is done.

"modprobe xfrm_user":
    xfrm_user_init()
        register_pernet_subsys()
            -> grab pernet_ops_rwsem
                ..
                netlink_table_grab()
                    calls schedule() as "nl_table_users" is non-zero

so modprobe is blocked because netlink_bind() increased
nl_table_users while also holding pernet_ops_rwsem.

"modprobe nf_conntrack_netlink" runs and inits nf_conntrack_netlink:
    ctnetlink_init()
        register_pernet_subsys()
            -> blocks on "pernet_ops_rwsem" thanks to xfrm_user module

both modprobe processes wait on one another -- neither can make
progress.

Switch netlink_bind() to "nowait" modprobe -- this releases the netlink
table lock, which then allows both modprobe instances to complete.

Reported-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Reported-by: Juliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/netfilter/nfnetlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 9adedba78eeac..044559c10e98e 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -495,7 +495,7 @@ static int nfnetlink_bind(struct net *net, int group)
 	ss = nfnetlink_get_subsys(type << 8);
 	rcu_read_unlock();
 	if (!ss)
-		request_module("nfnetlink-subsys-%d", type);
+		request_module_nowait("nfnetlink-subsys-%d", type);
 	return 0;
 }
 #endif
-- 
2.20.1

[PATCH AUTOSEL 4.4 03/17] mac80211: don't warn about CW params when not using them

[Sasha Levin]

From: Brian Norris <briannorris@chromium.org>

[ Upstream commit d2b3fe42bc629c2d4002f652b3abdfb2e72991c7 ]

ieee80211_set_wmm_default() normally sets up the initial CW min/max for
each queue, except that it skips doing this if the driver doesn't
support ->conf_tx. We still end up calling drv_conf_tx() in some cases
(e.g., ieee80211_reconfig()), which also still won't do anything
useful...except it complains here about the invalid CW parameters.

Let's just skip the WARN if we weren't going to do anything useful with
the parameters.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20190718015712.197499-1-briannorris@chromium.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mac80211/driver-ops.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/mac80211/driver-ops.c b/net/mac80211/driver-ops.c
index c258f1041d330..df2e4e3112177 100644
--- a/net/mac80211/driver-ops.c
+++ b/net/mac80211/driver-ops.c
@@ -169,11 +169,16 @@ int drv_conf_tx(struct ieee80211_local *local,
 	if (!check_sdata_in_driver(sdata))
 		return -EIO;
 
-	if (WARN_ONCE(params->cw_min == 0 ||
-		      params->cw_min > params->cw_max,
-		      "%s: invalid CW_min/CW_max: %d/%d\n",
-		      sdata->name, params->cw_min, params->cw_max))
+	if (params->cw_min == 0 || params->cw_min > params->cw_max) {
+		/*
+		 * If we can't configure hardware anyway, don't warn. We may
+		 * never have initialized the CW parameters.
+		 */
+		WARN_ONCE(local->ops->conf_tx,
+			  "%s: invalid CW_min/CW_max: %d/%d\n",
+			  sdata->name, params->cw_min, params->cw_max);
 		return -EINVAL;
+	}
 
 	trace_drv_conf_tx(local, sdata, ac, params);
 	if (local->ops->conf_tx)
-- 
2.20.1