Commit a0eea5f1 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: fix memory leak on address flush 



The endpoint cleanup path is prone to a memory leak, as reported
by syzkaller:

 BUG: memory leak
 unreferenced object 0xffff88810680ea00 (size 64):
   comm "syz-executor.6", pid 6191, jiffies 4295756280 (age 24.138s)
   hex dump (first 32 bytes):
     58 75 7d 3c 80 88 ff ff 22 01 00 00 00 00 ad de  Xu}<....".......
     01 00 02 00 00 00 00 00 ac 1e 00 07 00 00 00 00  ................
   backtrace:
     [<0000000072a9f72a>] kmalloc include/linux/slab.h:591 [inline]
     [<0000000072a9f72a>] mptcp_nl_cmd_add_addr+0x287/0x9f0 net/mptcp/pm_netlink.c:1170
     [<00000000f6e931bf>] genl_family_rcv_msg_doit.isra.0+0x225/0x340 net/netlink/genetlink.c:731
     [<00000000f1504a2c>] genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
     [<00000000f1504a2c>] genl_rcv_msg+0x341/0x5b0 net/netlink/genetlink.c:792
     [<0000000097e76f6a>] netlink_rcv_skb+0x148/0x430 net/netlink/af_netlink.c:2504
     [<00000000ceefa2b8>] genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
     [<000000008ff91aec>] netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
     [<000000008ff91aec>] netlink_unicast+0x537/0x750 net/netlink/af_netlink.c:1340
     [<0000000041682c35>] netlink_sendmsg+0x846/0xd80 net/netlink/af_netlink.c:1929
     [<00000000df3aa8e7>] sock_sendmsg_nosec net/socket.c:704 [inline]
     [<00000000df3aa8e7>] sock_sendmsg+0x14e/0x190 net/socket.c:724
     [<000000002154c54c>] ____sys_sendmsg+0x709/0x870 net/socket.c:2403
     [<000000001aab01d7>] ___sys_sendmsg+0xff/0x170 net/socket.c:2457
     [<00000000fa3b1446>] __sys_sendmsg+0xe5/0x1b0 net/socket.c:2486
     [<00000000db2ee9c7>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
     [<00000000db2ee9c7>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80
     [<000000005873517d>] entry_SYSCALL_64_after_hwframe+0x44/0xae

We should not require an allocation to cleanup stuff.

Rework the code a bit so that the additional RCU work is no more needed.

Fixes: 1729cf18 ("mptcp: create the listening socket for new port")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fb4b1373

net/mptcp/pm_netlink.c

+12 −32
Original line number Diff line number Diff line
@@ -1135,37 +1135,13 @@ static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net, 
	return 0;

}



struct addr_entry_release_work {

	struct rcu_work	rwork;

	struct mptcp_pm_addr_entry *entry;

};



static void mptcp_pm_release_addr_entry(struct work_struct *work)

/* caller must ensure the RCU grace period is already elapsed */

static void __mptcp_pm_release_addr_entry(struct mptcp_pm_addr_entry *entry)

{

	struct addr_entry_release_work *w;

	struct mptcp_pm_addr_entry *entry;



	w = container_of(to_rcu_work(work), struct addr_entry_release_work, rwork);

	entry = w->entry;

	if (entry) {

	if (entry->lsk)

		sock_release(entry->lsk);

	kfree(entry);

}

	kfree(w);

}



static void mptcp_pm_free_addr_entry(struct mptcp_pm_addr_entry *entry)

{

	struct addr_entry_release_work *w;



	w = kmalloc(sizeof(*w), GFP_ATOMIC);

	if (w) {

		INIT_RCU_WORK(&w->rwork, mptcp_pm_release_addr_entry);

		w->entry = entry;

		queue_rcu_work(system_wq, &w->rwork);

	}

}



static int mptcp_nl_remove_id_zero_address(struct net *net,

					   struct mptcp_addr_info *addr)
@@ -1244,7 +1220,8 @@ static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info) 
	spin_unlock_bh(&pernet->lock);



	mptcp_nl_remove_subflow_and_signal_addr(sock_net(skb->sk), &entry->addr);

	mptcp_pm_free_addr_entry(entry);

	synchronize_rcu();

	__mptcp_pm_release_addr_entry(entry);



	return ret;

}
@@ -1297,6 +1274,7 @@ static void mptcp_nl_remove_addrs_list(struct net *net, 
	}

}



/* caller must ensure the RCU grace period is already elapsed */

static void __flush_addrs(struct list_head *list)

{

	while (!list_empty(list)) {
@@ -1305,7 +1283,7 @@ static void __flush_addrs(struct list_head *list) 
		cur = list_entry(list->next,

				 struct mptcp_pm_addr_entry, list);

		list_del_rcu(&cur->list);

		mptcp_pm_free_addr_entry(cur);

		__mptcp_pm_release_addr_entry(cur);

	}

}
@@ -1329,6 +1307,7 @@ static int mptcp_nl_cmd_flush_addrs(struct sk_buff *skb, struct genl_info *info) 
	bitmap_zero(pernet->id_bitmap, MAX_ADDR_ID + 1);

	spin_unlock_bh(&pernet->lock);

	mptcp_nl_remove_addrs_list(sock_net(skb->sk), &free_list);

	synchronize_rcu();

	__flush_addrs(&free_list);

	return 0;

}
@@ -1939,7 +1918,8 @@ static void __net_exit pm_nl_exit_net(struct list_head *net_list) 
		struct pm_nl_pernet *pernet = net_generic(net, pm_nl_pernet_id);



		/* net is removed from namespace list, can't race with

		 * other modifiers

		 * other modifiers, also netns core already waited for a

		 * RCU grace period.

		 */

		__flush_addrs(&pernet->local_addr_list);

	}