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Miller" , Jakub Kicinski Cc: netdev , Eric Dumazet , Eric Dumazet , syzbot Subject: [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce() Date: Mon, 21 Jun 2021 07:44:17 -0700 Message-Id: <20210621144417.694367-1-eric.dumazet@gmail.com> X-Mailer: git-send-email 2.32.0.288.g62a8d224e6-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Eric Dumazet syzbot complained in neigh_reduce(), because rcu_read_lock_bh() is treated differently than rcu_read_lock() WARNING: suspicious RCU usage 5.13.0-rc6-syzkaller #0 Not tainted ----------------------------- include/net/addrconf.h:313 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by kworker/0:0/5: #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline] #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2247 #1: ffffc90000ca7da8 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2251 #2: ffffffff8bf795c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3130 net/core/dev.c:4180 stack backtrace: CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.13.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events ipvlan_process_multicast Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 __in6_dev_get include/net/addrconf.h:313 [inline] __in6_dev_get include/net/addrconf.h:311 [inline] neigh_reduce drivers/net/vxlan.c:2167 [inline] vxlan_xmit+0x34d5/0x4c30 drivers/net/vxlan.c:2919 __netdev_start_xmit include/linux/netdevice.h:4944 [inline] netdev_start_xmit include/linux/netdevice.h:4958 [inline] xmit_one net/core/dev.c:3654 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3670 __dev_queue_xmit+0x2133/0x3130 net/core/dev.c:4246 ipvlan_process_multicast+0xa99/0xd70 drivers/net/ipvlan/ipvlan_core.c:287 process_one_work+0x98d/0x1600 kernel/workqueue.c:2276 worker_thread+0x64c/0x1120 kernel/workqueue.c:2422 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Fixes: f564f45c4518 ("vxlan: add ipv6 proxy support") Signed-off-by: Eric Dumazet Reported-by: syzbot --- drivers/net/vxlan.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 02a14f1b938ad50fc28044b7670ba5f6bf924345..5a8df5a195cb5700c45b4785355ef8ed84866052 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -2164,6 +2164,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) struct neighbour *n; struct nd_msg *msg; + rcu_read_lock(); in6_dev = __in6_dev_get(dev); if (!in6_dev) goto out; @@ -2215,6 +2216,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) } out: + rcu_read_unlock(); consume_skb(skb); return NETDEV_TX_OK; }