[PATCH 5.10 390/406] net: ipv4: fix one memleak in __inet_del_ifa()

Greg Kroah-Hartman
2023-09-17T19:43:24Z

From: Liu Jian <liujian56@huawei.com>

[ Upstream commit ac28b1ec6135649b5d78b028e47264cb3ebca5ea ]

I got the below warning when do fuzzing test:
unregister_netdevice: waiting for bond0 to become free. Usage count = 2

It can be repoduced via:

ip link add bond0 type bond
sysctl -w net.ipv4.conf.bond0.promote_secondaries=1
ip addr add 4.117.174.103/0 scope 0x40 dev bond0
ip addr add 192.168.100.111/255.255.255.254 scope 0 dev bond0
ip addr add 0.0.0.4/0 scope 0x40 secondary dev bond0
ip addr del 4.117.174.103/0 scope 0x40 dev bond0
ip link delete bond0 type bond

In this reproduction test case, an incorrect 'last_prim' is found in
__inet_del_ifa(), as a result, the secondary address(0.0.0.4/0 scope 0x40)
is lost. The memory of the secondary address is leaked and the reference of
in_device and net_device is leaked.

Fix this problem:
Look for 'last_prim' starting at location of the deleted IP and inserting
the promoted IP into the location of 'last_prim'.

Fixes: 0ff60a45678e ("[IPV4]: Fix secondary IP addresses after promotion")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/devinet.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 88b6120878cd9..da1ca8081c035 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -351,14 +351,14 @@ static void __inet_del_ifa(struct in_device *in_dev,
{
struct in_ifaddr *promote = NULL;
struct in_ifaddr *ifa, *ifa1;
- struct in_ifaddr *last_prim;
+ struct in_ifaddr __rcu **last_prim;
struct in_ifaddr *prev_prom = NULL;
int do_promote = IN_DEV_PROMOTE_SECONDARIES(in_dev);

ASSERT_RTNL();

ifa1 = rtnl_dereference(*ifap);
- last_prim = rtnl_dereference(in_dev->ifa_list);
+ last_prim = ifap;
if (in_dev->dead)
goto no_promotions;

@@ -372,7 +372,7 @@ static void __inet_del_ifa(struct in_device *in_dev,
while ((ifa = rtnl_dereference(*ifap1)) != NULL) {
if (!(ifa->ifa_flags & IFA_F_SECONDARY) &&
ifa1->ifa_scope <= ifa->ifa_scope)
- last_prim = ifa;
+ last_prim = &ifa->ifa_next;

if (!(ifa->ifa_flags & IFA_F_SECONDARY) ||
ifa1->ifa_mask != ifa->ifa_mask ||
@@ -436,9 +436,9 @@ static void __inet_del_ifa(struct in_device *in_dev,

rcu_assign_pointer(prev_prom->ifa_next, next_sec);

- last_sec = rtnl_dereference(last_prim->ifa_next);
+ last_sec = rtnl_dereference(*last_prim);
rcu_assign_pointer(promote->ifa_next, last_sec);
- rcu_assign_pointer(last_prim->ifa_next, promote);
+ rcu_assign_pointer(*last_prim, promote);
}

promote->ifa_flags &= ~IFA_F_SECONDARY;
--
2.40.1