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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Florian Westphal <fw@strlen.de>,
	Thomas Jarosch <thomas.jarosch@intra2net.com>,
	Juliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Sasha Levin <sashal@kernel.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 01/42] netfilter: nfnetlink: avoid deadlock due to synchronous request_module
Date: Fri,  2 Aug 2019 09:22:21 -0400
Message-ID: <20190802132302.13537-1-sashal@kernel.org> (raw)

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 916913454624f..7f2c1915763f8 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -575,7 +575,7 @@ 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


             reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-02 13:22 Sasha Levin [this message]
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 02/42] vfio-ccw: Set pa_nr to 0 if memory allocation fails for pa_iova_pfn Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 03/42] netfilter: Fix rpfilter dropping vrf packets by mistake Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 04/42] netfilter: conntrack: always store window size un-scaled Sasha Levin
2019-08-08  9:02   ` Thomas Jarosch
2019-08-14 10:19     ` Reindl Harald
2019-08-14 11:17       ` Jakub Jankowski
2019-08-14 17:01         ` Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 05/42] netfilter: nft_hash: fix symhash with modulus one Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 06/42] scripts/sphinx-pre-install: fix script for RHEL/CentOS Sasha Levin
2019-08-03 10:31   ` Alexander Kapshuk
2019-08-03 10:37     ` Mauro Carvalho Chehab
2019-08-03 12:09       ` Alexander Kapshuk
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 07/42] drm/amd/display: Wait for backlight programming completion in set backlight level Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 08/42] drm/amd/display: use encoder's engine id to find matched free audio device Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 09/42] drm/amd/display: Fix dc_create failure handling and 666 color depths Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 10/42] drm/amd/display: Only enable audio if speaker allocation exists Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 11/42] drm/amd/display: Increase size of audios array Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 12/42] iscsi_ibft: make ISCSI_IBFT dependson ACPI instead of ISCSI_IBFT_FIND Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 13/42] nl80211: fix NL80211_HE_MAX_CAPABILITY_LEN Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 14/42] mac80211: don't warn about CW params when not using them Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 15/42] allocate_flower_entry: should check for null deref Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 16/42] hwmon: (nct6775) Fix register address and added missed tolerance for nct6106 Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 17/42] x86/mm: Check for pfn instead of page in vmalloc_sync_one() Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 18/42] x86/mm: Sync also unmappings in vmalloc_sync_all() Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 19/42] drm/msm: stop abusing dma_map/unmap for cache Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 20/42] drm: silence variable 'conn' set but not used Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 21/42] cpufreq/pasemi: fix use-after-free in pas_cpufreq_cpu_init() Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 22/42] s390/qdio: add sanity checks to the fast-requeue path Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 23/42] ALSA: compress: Fix regression on compressed capture streams Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 24/42] ALSA: compress: Prevent bypasses of set_params Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 25/42] ALSA: compress: Don't allow paritial drain operations on capture streams Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 26/42] ALSA: compress: Be more restrictive about when a drain is allowed Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 27/42] perf tools: Fix proper buffer size for feature processing Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 28/42] perf probe: Avoid calling freeing routine multiple times for same pointer Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 29/42] drbd: dynamically allocate shash descriptor Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 30/42] ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id() Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 31/42] nvme: fix multipath crash when ANA is deactivated Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 32/42] ARM: davinci: fix sleep.S build error on ARMv4 Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 33/42] ARM: dts: bcm: bcm47094: add missing #cells for mdio-bus-mux Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 34/42] scsi: megaraid_sas: fix panic on loading firmware crashdump Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 35/42] scsi: ibmvfc: fix WARN_ON during event pool release Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 36/42] scsi: scsi_dh_alua: always use a 2 second delay before retrying RTPG Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 37/42] test_firmware: fix a memory leak bug Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 38/42] sched/fair: Don't free p->numa_faults with concurrent readers Sasha Levin
2019-08-02 13:22 ` [PATCH AUTOSEL 4.19 39/42] sched/fair: Use RCU accessors consistently for ->numa_group Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.19 40/42] tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.19 41/42] perf/core: Fix creating kernel counters for PMUs that override event->cpu Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.19 42/42] s390/dma: provide proper ARCH_ZONE_DMA_BITS value Sasha Levin

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