Ido Schimmel 3106a08475 nexthop: Fix memory leaks in nexthop notification chain listeners ... syzkaller discovered memory leaks [1] that can be reduced to the following commands: # ip nexthop add id 1 blackhole # devlink dev reload pci/0000:06:00.0 As part of the reload flow, mlxsw will unregister its netdevs and then unregister from the nexthop notification chain. Before unregistering from the notification chain, mlxsw will receive delete notifications for nexthop objects using netdevs registered by mlxsw or their uppers. mlxsw will not receive notifications for nexthops using netdevs that are not dismantled as part of the reload flow. For example, the blackhole nexthop above that internally uses the loopback netdev as its nexthop device. One way to fix this problem is to have listeners flush their nexthop tables after unregistering from the notification chain. This is error-prone as evident by this patch and also not symmetric with the registration path where a listener receives a dump of all the existing nexthops. Therefore, fix this problem by replaying delete notifications for the listener being unregistered. This is symmetric to the registration path and also consistent with the netdev notification chain. The above means that unregister_nexthop_notifier(), like register_nexthop_notifier(), will have to take RTNL in order to iterate over the existing nexthops and that any callers of the function cannot hold RTNL. This is true for mlxsw and netdevsim, but not for the VXLAN driver. To avoid a deadlock, change the latter to unregister its nexthop listener without holding RTNL, making it symmetric to the registration path. [1] unreferenced object 0xffff88806173d600 (size 512): comm "syz-executor.0", pid 1290, jiffies 4295583142 (age 143.507s) hex dump (first 32 bytes): 41 9d 1e 60 80 88 ff ff 08 d6 73 61 80 88 ff ff A..`......sa.... 08 d6 73 61 80 88 ff ff 01 00 00 00 00 00 00 00 ..sa............ backtrace: [<ffffffff81a6b576>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] [<ffffffff81a6b576>] slab_post_alloc_hook+0x96/0x490 mm/slab.h:522 [<ffffffff81a716d3>] slab_alloc_node mm/slub.c:3206 [inline] [<ffffffff81a716d3>] slab_alloc mm/slub.c:3214 [inline] [<ffffffff81a716d3>] kmem_cache_alloc_trace+0x163/0x370 mm/slub.c:3231 [<ffffffff82e8681a>] kmalloc include/linux/slab.h:591 [inline] [<ffffffff82e8681a>] kzalloc include/linux/slab.h:721 [inline] [<ffffffff82e8681a>] mlxsw_sp_nexthop_obj_group_create drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:4918 [inline] [<ffffffff82e8681a>] mlxsw_sp_nexthop_obj_new drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:5054 [inline] [<ffffffff82e8681a>] mlxsw_sp_nexthop_obj_event+0x59a/0x2910 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:5239 [<ffffffff813ef67d>] notifier_call_chain+0xbd/0x210 kernel/notifier.c:83 [<ffffffff813f0662>] blocking_notifier_call_chain kernel/notifier.c:318 [inline] [<ffffffff813f0662>] blocking_notifier_call_chain+0x72/0xa0 kernel/notifier.c:306 [<ffffffff8384b9c6>] call_nexthop_notifiers+0x156/0x310 net/ipv4/nexthop.c:244 [<ffffffff83852bd8>] insert_nexthop net/ipv4/nexthop.c:2336 [inline] [<ffffffff83852bd8>] nexthop_add net/ipv4/nexthop.c:2644 [inline] [<ffffffff83852bd8>] rtm_new_nexthop+0x14e8/0x4d10 net/ipv4/nexthop.c:2913 [<ffffffff833e9a78>] rtnetlink_rcv_msg+0x448/0xbf0 net/core/rtnetlink.c:5572 [<ffffffff83608703>] netlink_rcv_skb+0x173/0x480 net/netlink/af_netlink.c:2504 [<ffffffff833de032>] rtnetlink_rcv+0x22/0x30 net/core/rtnetlink.c:5590 [<ffffffff836069de>] netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] [<ffffffff836069de>] netlink_unicast+0x5ae/0x7f0 net/netlink/af_netlink.c:1340 [<ffffffff83607501>] netlink_sendmsg+0x8e1/0xe30 net/netlink/af_netlink.c:1929 [<ffffffff832fde84>] sock_sendmsg_nosec net/socket.c:704 [inline] [<ffffffff832fde84>] sock_sendmsg net/socket.c:724 [inline] [<ffffffff832fde84>] ____sys_sendmsg+0x874/0x9f0 net/socket.c:2409 [<ffffffff83304a44>] ___sys_sendmsg+0x104/0x170 net/socket.c:2463 [<ffffffff83304c01>] __sys_sendmsg+0x111/0x1f0 net/socket.c:2492 [<ffffffff83304d5d>] __do_sys_sendmsg net/socket.c:2501 [inline] [<ffffffff83304d5d>] __se_sys_sendmsg net/socket.c:2499 [inline] [<ffffffff83304d5d>] __x64_sys_sendmsg+0x7d/0xc0 net/socket.c:2499 Fixes: 2a014b200b ("mlxsw: spectrum_router: Add support for nexthop objects") Signed-off-by: Ido Schimmel <idosch@nvidia.com> Reviewed-by: Petr Machata <petrm@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2021-09-23 12:33:22 +01:00
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6lowpan
9p
802
8021q
appletalk
atm
ax25
batman-adv
bluetooth
bpf
bpfilter
bridge
caif	net-caif: avoid user-triggerable WARN_ON(1)	2021-09-14 12:51:15 +01:00
can
ceph
core	napi: fix race inside napi_enable	2021-09-20 09:41:29 +01:00
dcb
dccp
decnet
dns_resolver
dsa	net: dsa: don't allocate the slave_mii_bus using devres	2021-09-21 13:52:16 +01:00
ethernet
ethtool
hsr
ieee802154
ife
ipv4	nexthop: Fix memory leaks in nexthop notification chain listeners	2021-09-23 12:33:22 +01:00
ipv6	ipv6: delay fib6_sernum increase in fib6_add	2021-09-13 13:00:53 +01:00
iucv
kcm
key
l2tp
l3mdev
lapb
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mptcp	mptcp: ensure tx skbs always have the MPTCP ext	2021-09-22 14:39:41 +01:00
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rose
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smc	net/smc: fix 'workqueue leaked lock' in smc_conn_abort_work	2021-09-21 10:54:16 +01:00
strparser
sunrpc
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tipc	tipc: increase timeout in tipc_sk_enqueue()	2021-09-13 12:43:10 +01:00
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