From c79189c85d69a0332fcaffa3291257e43e703dd9 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Wed, 14 Sep 2022 10:53:38 +0300 Subject: [PATCH] ipmr: Always call ip{,6}_mr_forward() from RCU read-side critical section These functions expect to be called from RCU read-side critical section, but this only happens when invoked from the data path via ip{,6}_mr_input(). They can also be invoked from process context in response to user space adding a multicast route which resolves a cache entry with queued packets [1][2]. Fix by adding missing rcu_read_lock() / rcu_read_unlock() in these call paths. [1] WARNING: suspicious RCU usage 6.0.0-rc3-custom-15969-g049d233c8bcc-dirty #1387 Not tainted ----------------------------- net/ipv4/ipmr.c:84 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by smcrouted/246: #0: ffffffff862389b0 (rtnl_mutex){+.+.}-{3:3}, at: ip_mroute_setsockopt+0x11c/0x1420 stack backtrace: CPU: 0 PID: 246 Comm: smcrouted Not tainted 6.0.0-rc3-custom-15969-g049d233c8bcc-dirty #1387 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 Call Trace: dump_stack_lvl+0x91/0xb9 vif_dev_read+0xbf/0xd0 ipmr_queue_xmit+0x135/0x1ab0 ip_mr_forward+0xe7b/0x13d0 ipmr_mfc_add+0x1a06/0x2ad0 ip_mroute_setsockopt+0x5c1/0x1420 do_ip_setsockopt+0x23d/0x37f0 ip_setsockopt+0x56/0x80 raw_setsockopt+0x219/0x290 __sys_setsockopt+0x236/0x4d0 __x64_sys_setsockopt+0xbe/0x160 do_syscall_64+0x34/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [2] WARNING: suspicious RCU usage 6.0.0-rc3-custom-15969-g049d233c8bcc-dirty #1387 Not tainted ----------------------------- net/ipv6/ip6mr.c:69 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by smcrouted/246: #0: ffffffff862389b0 (rtnl_mutex){+.+.}-{3:3}, at: ip6_mroute_setsockopt+0x6b9/0x2630 stack backtrace: CPU: 1 PID: 246 Comm: smcrouted Not tainted 6.0.0-rc3-custom-15969-g049d233c8bcc-dirty #1387 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 Call Trace: dump_stack_lvl+0x91/0xb9 vif_dev_read+0xbf/0xd0 ip6mr_forward2.isra.0+0xc9/0x1160 ip6_mr_forward+0xef0/0x13f0 ip6mr_mfc_add+0x1ff2/0x31f0 ip6_mroute_setsockopt+0x1825/0x2630 do_ipv6_setsockopt+0x462/0x4440 ipv6_setsockopt+0x105/0x140 rawv6_setsockopt+0xd8/0x690 __sys_setsockopt+0x236/0x4d0 __x64_sys_setsockopt+0xbe/0x160 do_syscall_64+0x34/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: f5fd7c2684de ("ipmr: add rcu protection over (struct vif_device)->dev") Signed-off-by: Ido Schimmel Signed-off-by: Jakub Kicinski --- net/ipv4/ipmr.c | 2 ++ net/ipv6/ip6mr.c | 5 ++++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index 73651d17e51f3..e11d6b0b62b76 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1004,7 +1004,9 @@ static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt, rtnl_unicast(skb, net, NETLINK_CB(skb).portid); } else { + rcu_read_lock(); ip_mr_forward(net, mrt, skb->dev, skb, c, 0); + rcu_read_unlock(); } } } diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index a9ba41648e368..858fd8a28b5b2 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -1028,8 +1028,11 @@ static void ip6mr_cache_resolve(struct net *net, struct mr_table *mrt, ((struct nlmsgerr *)nlmsg_data(nlh))->error = -EMSGSIZE; } rtnl_unicast(skb, net, NETLINK_CB(skb).portid); - } else + } else { + rcu_read_lock(); ip6_mr_forward(net, mrt, skb->dev, skb, c); + rcu_read_unlock(); + } } } -- 2.39.5