[PATCH 4.19 33/86] bonding: check error value of register_netdevice() immediately

Greg Kroah-Hartman
2020-07-27T14:38:14Z

From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit 544f287b84959203367cd29e16e772717612fab4 ]

If register_netdevice() is failed, net_device should not be used
because variables are uninitialized or freed.
So, the routine should be stopped immediately.
But, bond_create() doesn't check return value of register_netdevice()
immediately. That will result in a panic because of using uninitialized
or freed memory.

Test commands:
modprobe netdev-notifier-error-inject
echo -22 > /sys/kernel/debug/notifier-error-inject/netdev/\
actions/NETDEV_REGISTER/error
modprobe bonding max_bonds=3

Splat looks like:
[ 375.028492][ T193] general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[ 375.033207][ T193] CPU: 2 PID: 193 Comm: kworker/2:2 Not tainted 5.8.0-rc4+ #645
[ 375.036068][ T193] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 375.039673][ T193] Workqueue: events linkwatch_event
[ 375.041557][ T193] RIP: 0010:dev_activate+0x4a/0x340
[ 375.043381][ T193] Code: 40 a8 04 0f 85 db 00 00 00 8b 83 08 04 00 00 85 c0 0f 84 0d 01 00 00 31 d2 89 d0 48 8d 04 40 48 c1 e0 07 48 03 83 00 04 00 00 <48> 8b 48 10 f6 41 10 01 75 08 f0 80 a1 a0 01 00 00 fd 48 89 48 08
[ 375.050267][ T193] RSP: 0018:ffff9f8facfcfdd8 EFLAGS: 00010202
[ 375.052410][ T193] RAX: 6b6b6b6b6b6b6b6b RBX: ffff9f8fae6ea000 RCX: 0000000000000006
[ 375.055178][ T193] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9f8fae6ea000
[ 375.057762][ T193] RBP: ffff9f8fae6ea000 R08: 0000000000000000 R09: 0000000000000000
[ 375.059810][ T193] R10: 0000000000000001 R11: 0000000000000000 R12: ffff9f8facfcfe08
[ 375.061892][ T193] R13: ffffffff883587e0 R14: 0000000000000000 R15: ffff9f8fae6ea580
[ 375.063931][ T193] FS: 0000000000000000(0000) GS:ffff9f8fbae00000(0000) knlGS:0000000000000000
[ 375.066239][ T193] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 375.067841][ T193] CR2: 00007f2f542167a0 CR3: 000000012cee6002 CR4: 00000000003606e0
[ 375.069657][ T193] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 375.071471][ T193] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 375.073269][ T193] Call Trace:
[ 375.074005][ T193] linkwatch_do_dev+0x4d/0x50
[ 375.075052][ T193] __linkwatch_run_queue+0x10b/0x200
[ 375.076244][ T193] linkwatch_event+0x21/0x30
[ 375.077274][ T193] process_one_work+0x252/0x600
[ 375.078379][ T193] ? process_one_work+0x600/0x600
[ 375.079518][ T193] worker_thread+0x3c/0x380
[ 375.080534][ T193] ? process_one_work+0x600/0x600
[ 375.081668][ T193] kthread+0x139/0x150
[ 375.082567][ T193] ? kthread_park+0x90/0x90
[ 375.083567][ T193] ret_from_fork+0x22/0x30

Fixes: e826eafa65c6 ("bonding: Call netif_carrier_off after register_netdevice")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/bonding/bond_main.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index f57b86f1373d4..11429df743067 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4817,15 +4817,19 @@ int bond_create(struct net *net, const char *name)
bond_dev->rtnl_link_ops = &bond_link_ops;

res = register_netdevice(bond_dev);
+ if (res < 0) {
+ free_netdev(bond_dev);
+ rtnl_unlock();
+
+ return res;
+ }

netif_carrier_off(bond_dev);

bond_work_init_all(bond);

rtnl_unlock();
- if (res < 0)
- free_netdev(bond_dev);
- return res;
+ return 0;
}

static int __net_init bond_net_init(struct net *net)
--
2.25.1