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Subject[PATCH net] net: marvell: prestera: fix incorrect structure access
Date
In line:
upper = info->upper_dev;
We access upper_dev field, which is related only for particular events
(e.g. event == NETDEV_CHANGEUPPER). So, this line cause invalid memory
access for another events,
when ptr is not netdev_notifier_changeupper_info.

The KASAN logs are as follows:

[ 30.123165] BUG: KASAN: stack-out-of-bounds in prestera_netdev_port_event.constprop.0+0x68/0x538 [prestera]
[ 30.133336] Read of size 8 at addr ffff80000cf772b0 by task udevd/778
[ 30.139866]
[ 30.141398] CPU: 0 PID: 778 Comm: udevd Not tainted 5.16.0-rc3 #6
[ 30.147588] Hardware name: DNI AmazonGo1 A7040 board (DT)
[ 30.153056] Call trace:
[ 30.155547] dump_backtrace+0x0/0x2c0
[ 30.159320] show_stack+0x18/0x30
[ 30.162729] dump_stack_lvl+0x68/0x84
[ 30.166491] print_address_description.constprop.0+0x74/0x2b8
[ 30.172346] kasan_report+0x1e8/0x250
[ 30.176102] __asan_load8+0x98/0xe0
[ 30.179682] prestera_netdev_port_event.constprop.0+0x68/0x538 [prestera]
[ 30.186847] prestera_netdev_event_handler+0x1b4/0x1c0 [prestera]
[ 30.193313] raw_notifier_call_chain+0x74/0xa0
[ 30.197860] call_netdevice_notifiers_info+0x68/0xc0
[ 30.202924] register_netdevice+0x3cc/0x760
[ 30.207190] register_netdev+0x24/0x50
[ 30.211015] prestera_device_register+0x8a0/0xba0 [prestera]

Fixes: 3d5048cc54bd ("net: marvell: prestera: move netdev topology validation to prestera_main")
Signed-off-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
---
.../ethernet/marvell/prestera/prestera_main.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/marvell/prestera/prestera_main.c b/drivers/net/ethernet/marvell/prestera/prestera_main.c
index a0dbad5cb88d..9064353ea0fb 100644
--- a/drivers/net/ethernet/marvell/prestera/prestera_main.c
+++ b/drivers/net/ethernet/marvell/prestera/prestera_main.c
@@ -765,23 +765,27 @@ static int prestera_netdev_port_event(struct net_device *lower,
struct net_device *dev,
unsigned long event, void *ptr)
{
- struct netdev_notifier_changeupper_info *info = ptr;
+ struct netdev_notifier_info *info = ptr;
+ struct netdev_notifier_changeupper_info *cu_info;
struct prestera_port *port = netdev_priv(dev);
struct netlink_ext_ack *extack;
struct net_device *upper;

- extack = netdev_notifier_info_to_extack(&info->info);
- upper = info->upper_dev;
+ extack = netdev_notifier_info_to_extack(info);
+ cu_info = container_of(info,
+ struct netdev_notifier_changeupper_info,
+ info);

switch (event) {
case NETDEV_PRECHANGEUPPER:
+ upper = cu_info->upper_dev;
if (!netif_is_bridge_master(upper) &&
!netif_is_lag_master(upper)) {
NL_SET_ERR_MSG_MOD(extack, "Unknown upper device type");
return -EINVAL;
}

- if (!info->linking)
+ if (!cu_info->linking)
break;

if (netdev_has_any_upper_dev(upper)) {
@@ -790,7 +794,7 @@ static int prestera_netdev_port_event(struct net_device *lower,
}

if (netif_is_lag_master(upper) &&
- !prestera_lag_master_check(upper, info->upper_info, extack))
+ !prestera_lag_master_check(upper, cu_info->upper_info, extack))
return -EOPNOTSUPP;
if (netif_is_lag_master(upper) && vlan_uses_dev(dev)) {
NL_SET_ERR_MSG_MOD(extack,
@@ -806,14 +810,15 @@ static int prestera_netdev_port_event(struct net_device *lower,
break;

case NETDEV_CHANGEUPPER:
+ upper = cu_info->upper_dev;
if (netif_is_bridge_master(upper)) {
- if (info->linking)
+ if (cu_info->linking)
return prestera_bridge_port_join(upper, port,
extack);
else
prestera_bridge_port_leave(upper, port);
} else if (netif_is_lag_master(upper)) {
- if (info->linking)
+ if (cu_info->linking)
return prestera_lag_port_add(port, upper);
else
prestera_lag_port_del(port);
--
2.17.1
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