[PATCH 4.18 32/35] ip_vti: fix a null pointer deferrence when create vti fallback tunnel
From: Greg Kroah-Hartman
Date: Tue Aug 21 2018 - 02:23:21 EST
4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
[ Upstream commit cd1aa9c2c665cafbd05b83507d3f1096f3912aa4 ]
After set fb_tunnels_only_for_init_net to 1, the itn->fb_tunnel_dev will
be NULL and will cause following crash:
[ 2742.849298] BUG: unable to handle kernel NULL pointer dereference at 0000000000000941
[ 2742.851380] PGD 800000042c21a067 P4D 800000042c21a067 PUD 42aaed067 PMD 0
[ 2742.852818] Oops: 0002 [#1] SMP PTI
[ 2742.853570] CPU: 7 PID: 2484 Comm: unshare Kdump: loaded Not tainted 4.18.0-rc8+ #2
[ 2742.855163] Hardware name: Fedora Project OpenStack Nova, BIOS seabios-1.7.5-11.el7 04/01/2014
[ 2742.856970] RIP: 0010:vti_init_net+0x3a/0x50 [ip_vti]
[ 2742.858034] Code: 90 83 c0 48 c7 c2 20 a1 83 c0 48 89 fb e8 6e 3b f6 ff 85 c0 75 22 8b 0d f4 19 00 00 48 8b 93 00 14 00 00 48 8b 14 ca 48 8b 12 <c6> 82 41 09 00 00 04 c6 82 38 09 00 00 45 5b c3 66 0f 1f 44 00 00
[ 2742.861940] RSP: 0018:ffff9be28207fde0 EFLAGS: 00010246
[ 2742.863044] RAX: 0000000000000000 RBX: ffff8a71ebed4980 RCX: 0000000000000013
[ 2742.864540] RDX: 0000000000000000 RSI: 0000000000000013 RDI: ffff8a71ebed4980
[ 2742.866020] RBP: ffff8a71ea717000 R08: ffffffffc083903c R09: ffff8a71ea717000
[ 2742.867505] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a71ebed4980
[ 2742.868987] R13: 0000000000000013 R14: ffff8a71ea5b49c0 R15: 0000000000000000
[ 2742.870473] FS: 00007f02266c9740(0000) GS:ffff8a71ffdc0000(0000) knlGS:0000000000000000
[ 2742.872143] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2742.873340] CR2: 0000000000000941 CR3: 000000042bc20006 CR4: 00000000001606e0
[ 2742.874821] Call Trace:
[ 2742.875358] ops_init+0x38/0xf0
[ 2742.876078] setup_net+0xd9/0x1f0
[ 2742.876789] copy_net_ns+0xb7/0x130
[ 2742.877538] create_new_namespaces+0x11a/0x1d0
[ 2742.878525] unshare_nsproxy_namespaces+0x55/0xa0
[ 2742.879526] ksys_unshare+0x1a7/0x330
[ 2742.880313] __x64_sys_unshare+0xe/0x20
[ 2742.881131] do_syscall_64+0x5b/0x180
[ 2742.881933] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reproduce:
echo 1 > /proc/sys/net/core/fb_tunnels_only_for_init_net
modprobe ip_vti
unshare -n
Fixes: 79134e6ce2c9 ("net: do not create fallback tunnels for non-default namespaces")
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/ip_vti.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -438,7 +438,8 @@ static int __net_init vti_init_net(struc
if (err)
return err;
itn = net_generic(net, vti_net_id);
- vti_fb_tunnel_init(itn->fb_tunnel_dev);
+ if (itn->fb_tunnel_dev)
+ vti_fb_tunnel_init(itn->fb_tunnel_dev);
return 0;
}