* [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net()
@ 2020-07-13 15:59 Wei Yongjun
2020-07-13 16:31 ` Eric Dumazet
2020-07-14 0:33 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Wei Yongjun @ 2020-07-13 15:59 UTC (permalink / raw)
To: hulkci, Eric Dumazet, Taehee Yoo, Alexey Kuznetsov,
Hideaki YOSHIFUJI, Jakub Kicinski
Cc: Wei Yongjun, netdev
KASAN report null-ptr-deref error when register_netdev() failed:
KASAN: null-ptr-deref in range [0x00000000000003c0-0x00000000000003c7]
CPU: 2 PID: 422 Comm: ip Not tainted 5.8.0-rc4+ #12
Call Trace:
ip6gre_init_net+0x4ab/0x580
? ip6gre_tunnel_uninit+0x3f0/0x3f0
ops_init+0xa8/0x3c0
setup_net+0x2de/0x7e0
? rcu_read_lock_bh_held+0xb0/0xb0
? ops_init+0x3c0/0x3c0
? kasan_unpoison_shadow+0x33/0x40
? __kasan_kmalloc.constprop.0+0xc2/0xd0
copy_net_ns+0x27d/0x530
create_new_namespaces+0x382/0xa30
unshare_nsproxy_namespaces+0xa1/0x1d0
ksys_unshare+0x39c/0x780
? walk_process_tree+0x2a0/0x2a0
? trace_hardirqs_on+0x4a/0x1b0
? _raw_spin_unlock_irq+0x1f/0x30
? syscall_trace_enter+0x1a7/0x330
? do_syscall_64+0x1c/0xa0
__x64_sys_unshare+0x2d/0x40
do_syscall_64+0x56/0xa0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
ip6gre_tunnel_uninit() has set 'ign->fb_tunnel_dev' to NULL, later
access to ign->fb_tunnel_dev cause null-ptr-deref. Fix it by saving
'ign->fb_tunnel_dev' to local variable ndev.
Fixes: dafabb6590cb ("ip6_gre: fix use-after-free in ip6gre_tunnel_lookup()")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 6532bde82b40..3a57fb9ce049 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1562,17 +1562,18 @@ static void ip6gre_destroy_tunnels(struct net *net, struct list_head *head)
static int __net_init ip6gre_init_net(struct net *net)
{
struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
+ struct net_device *ndev;
int err;
if (!net_has_fallback_tunnels(net))
return 0;
- ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
- NET_NAME_UNKNOWN,
- ip6gre_tunnel_setup);
- if (!ign->fb_tunnel_dev) {
+ ndev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
+ NET_NAME_UNKNOWN, ip6gre_tunnel_setup);
+ if (!ndev) {
err = -ENOMEM;
goto err_alloc_dev;
}
+ ign->fb_tunnel_dev = ndev;
dev_net_set(ign->fb_tunnel_dev, net);
/* FB netdevice is special: we have one, and only one per netns.
* Allowing to move it to another netns is clearly unsafe.
@@ -1592,7 +1593,7 @@ static int __net_init ip6gre_init_net(struct net *net)
return 0;
err_reg_dev:
- free_netdev(ign->fb_tunnel_dev);
+ free_netdev(ndev);
err_alloc_dev:
return err;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net()
2020-07-13 15:59 [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net() Wei Yongjun
@ 2020-07-13 16:31 ` Eric Dumazet
2020-07-14 0:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Eric Dumazet @ 2020-07-13 16:31 UTC (permalink / raw)
To: Wei Yongjun, hulkci, Eric Dumazet, Taehee Yoo, Alexey Kuznetsov,
Hideaki YOSHIFUJI, Jakub Kicinski
Cc: netdev
On 7/13/20 8:59 AM, Wei Yongjun wrote:
> KASAN report null-ptr-deref error when register_netdev() failed:
>
>
>
> ip6gre_tunnel_uninit() has set 'ign->fb_tunnel_dev' to NULL, later
> access to ign->fb_tunnel_dev cause null-ptr-deref. Fix it by saving
> 'ign->fb_tunnel_dev' to local variable ndev.
>
> Fixes: dafabb6590cb ("ip6_gre: fix use-after-free in ip6gre_tunnel_lookup()")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
>
Reviewed-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net()
2020-07-13 15:59 [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net() Wei Yongjun
2020-07-13 16:31 ` Eric Dumazet
@ 2020-07-14 0:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2020-07-14 0:33 UTC (permalink / raw)
To: weiyongjun1
Cc: hulkci, eric.dumazet, ap420073, kuznet, yoshfuji, kuba, netdev
From: Wei Yongjun <weiyongjun1@huawei.com>
Date: Mon, 13 Jul 2020 23:59:50 +0800
> KASAN report null-ptr-deref error when register_netdev() failed:
...
> ip6gre_tunnel_uninit() has set 'ign->fb_tunnel_dev' to NULL, later
> access to ign->fb_tunnel_dev cause null-ptr-deref. Fix it by saving
> 'ign->fb_tunnel_dev' to local variable ndev.
>
> Fixes: dafabb6590cb ("ip6_gre: fix use-after-free in ip6gre_tunnel_lookup()")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Applied and queued up for -stable.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-07-13 15:59 [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net() Wei Yongjun
2020-07-13 16:31 ` Eric Dumazet
2020-07-14 0:33 ` David Miller
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