2022-08-20 10:30:08

by Li Zhong

Subject: [PATCH v1] net/ipv6/addrconf.c: Check the return value of __in6_dev_get() in addrconf_type_change()

The function __in6_dev_get() could return NULL pointer. This needs to be
checked before used in ipv6_mc_remap() and ipv6_mc_unmap(). Otherwise it
could result in null pointer dereference.
---
net/ipv6/addrconf.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index b624e3d8c5f0..b5e490fe0bcd 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3718,6 +3718,9 @@ static void addrconf_type_change(struct net_device *dev, unsigned long event)

idev = __in6_dev_get(dev);

+ if(!idev)
+ return;
+
if (event == NETDEV_POST_TYPE_CHANGE)
ipv6_mc_remap(idev);
else if (event == NETDEV_PRE_TYPE_CHANGE)
--
2.25.1

2022-08-21 18:23:33

by Cong Wang

Subject: Re: [PATCH v1] net/ipv6/addrconf.c: Check the return value of __in6_dev_get() in addrconf_type_change()

On Sat, Aug 20, 2022 at 03:24:34AM -0700, lily wrote:
> The function __in6_dev_get() could return NULL pointer. This needs to be
> checked before used in ipv6_mc_remap() and ipv6_mc_unmap(). Otherwise it
> could result in null pointer dereference.

Its caller already checks it:

3689 if (idev)
3690 addrconf_type_change(dev, event);
3691 break;