mlxsw: spectrum_ipip: Fix memory leak when changing remote IPv6 address

In the Linux kernel, the following vulnerability has been resolved:

mlxsw: spectrum_ipip: Fix memory leak when changing remote IPv6 address

The device stores IPv6 addresses that are used for encapsulation in

linear memory that is managed by the driver.

Changing the remote address of an ip6gre net device never worked

properly, but since cited commit the following reproducer [1] would

result in a warning [2] and a memory leak [3]. The problem is that the

new remote address is never added by the driver to its hash table (and

therefore the device) and the old address is never removed from it.

Fix by programming the new address when the configuration of the ip6gre

net device changes and removing the old one. If the address did not

change, then the above would result in increasing the reference count of

the address and then decreasing it.

[1]

# ip link add name bla up type ip6gre local 2001:db8:1::1 remote 2001:db8:2::1 tos inherit ttl inherit

# ip link set dev bla type ip6gre remote 2001:db8:3::1

# ip link del dev bla

# devlink dev reload pci/0000:01:00.0

[2]

WARNING: CPU: 0 PID: 1682 at drivers/net/ethernet/mellanox/mlxsw/spectrum.c:3002 mlxsw_sp_ipv6_addr_put+0x140/0x1d0

Modules linked in:

CPU: 0 UID: 0 PID: 1682 Comm: ip Not tainted 6.12.0-rc3-custom-g86b5b55bc835 #151

Hardware name: Nvidia SN5600/VMOD0013, BIOS 5.13 05/31/2023

RIP: 0010:mlxsw_sp_ipv6_addr_put+0x140/0x1d0

[...]

Call Trace:

<TASK>

mlxsw_sp_router_netdevice_event+0x55f/0x1240

notifier_call_chain+0x5a/0xd0

call_netdevice_notifiers_info+0x39/0x90

unregister_netdevice_many_notify+0x63e/0x9d0

rtnl_dellink+0x16b/0x3a0

rtnetlink_rcv_msg+0x142/0x3f0

netlink_rcv_skb+0x50/0x100

netlink_unicast+0x242/0x390

netlink_sendmsg+0x1de/0x420

____sys_sendmsg+0x2bd/0x320

___sys_sendmsg+0x9a/0xe0

__sys_sendmsg+0x7a/0xd0

do_syscall_64+0x9e/0x1a0

entry_SYSCALL_64_after_hwframe+0x77/0x7f

[3]

unreferenced object 0xffff898081f597a0 (size 32):

comm "ip", pid 1626, jiffies 4294719324

hex dump (first 32 bytes):

20 01 0d b8 00 02 00 00 00 00 00 00 00 00 00 01 ...............

21 49 61 83 80 89 ff ff 00 00 00 00 01 00 00 00 !Ia.............

backtrace (crc fd9be911):

[<00000000df89c55d>] __kmalloc_cache_noprof+0x1da/0x260

[<00000000ff2a1ddb>] mlxsw_sp_ipv6_addr_kvdl_index_get+0x281/0x340

[<000000009ddd445d>] mlxsw_sp_router_netdevice_event+0x47b/0x1240

[<00000000743e7757>] notifier_call_chain+0x5a/0xd0

[<000000007c7b9e13>] call_netdevice_notifiers_info+0x39/0x90

[<000000002509645d>] register_netdevice+0x5f7/0x7a0

[<00000000c2e7d2a9>] ip6gre_newlink_common.isra.0+0x65/0x130

[<0000000087cd6d8d>] ip6gre_newlink+0x72/0x120

[<000000004df7c7cc>] rtnl_newlink+0x471/0xa20

[<0000000057ed632a>] rtnetlink_rcv_msg+0x142/0x3f0

[<0000000032e0d5b5>] netlink_rcv_skb+0x50/0x100

[<00000000908bca63>] netlink_unicast+0x242/0x390

[<00000000cdbe1c87>] netlink_sendmsg+0x1de/0x420

[<0000000011db153e>] ____sys_sendmsg+0x2bd/0x320

[<000000003b6d53eb>] ___sys_sendmsg+0x9a/0xe0

[<00000000cae27c62>] __sys_sendmsg+0x7a/0xd0