From 9e44a4e3e49ab99720e9396c3362f024b2b60074 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Thu, 27 Jun 2019 23:50:10 +0900 Subject: [PATCH] vxlan: do not destroy fdb if register_netdevice() is failed __vxlan_dev_create() destroys FDB using specific pointer which indicates a fdb when error occurs. But that pointer should not be used when register_netdevice() fails because register_netdevice() internally destroys fdb when error occurs. This patch makes vxlan_fdb_create() to do not link fdb entry to vxlan dev internally. Instead, a new function vxlan_fdb_link() is added to link fdb to vxlan dev. vxlan_fdb_link() is called after calling register_netdevice(). This routine can avoid situation that ->ndo_uninit() destroys fdb entry in error path of register_netdevice(). Hence, error path of __vxlan_dev_create() routine can have an opportunity to destroy default fdb entry by hand. Test command ip link add bonding_masters type vxlan id 0 group 239.1.1.1 \ dev enp0s9 dstport 4789 Splat looks like: [ 213.392816] kasan: GPF could be caused by NULL-ptr deref or user memory access [ 213.401257] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 213.402178] CPU: 0 PID: 1414 Comm: ip Not tainted 5.2.0-rc5+ #256 [ 213.402178] RIP: 0010:vxlan_fdb_destroy+0x120/0x220 [vxlan] [ 213.402178] Code: df 48 8b 2b 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 06 01 00 00 4c 8b 63 08 48 b8 00 00 00 00 00 fc d [ 213.402178] RSP: 0018:ffff88810cb9f0a0 EFLAGS: 00010202 [ 213.402178] RAX: dffffc0000000000 RBX: ffff888101d4a8c8 RCX: 0000000000000000 [ 213.402178] RDX: 1bd5a00000000040 RSI: ffff888101d4a8c8 RDI: ffff888101d4a8d0 [ 213.402178] RBP: 0000000000000000 R08: fffffbfff22b72d9 R09: 0000000000000000 [ 213.402178] R10: 00000000ffffffef R11: 0000000000000000 R12: dead000000000200 [ 213.402178] R13: ffff88810cb9f1f8 R14: ffff88810efccda0 R15: ffff88810efccda0 [ 213.402178] FS: 00007f7f6621a0c0(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000 [ 213.402178] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 213.402178] CR2: 000055746f0807d0 CR3: 00000001123e0000 CR4: 00000000001006f0 [ 213.402178] Call Trace: [ 213.402178] __vxlan_dev_create+0x3a9/0x7d0 [vxlan] [ 213.402178] ? vxlan_changelink+0x740/0x740 [vxlan] [ 213.402178] ? rcu_read_unlock+0x60/0x60 [vxlan] [ 213.402178] ? __kasan_kmalloc.constprop.3+0xa0/0xd0 [ 213.402178] vxlan_newlink+0x8d/0xc0 [vxlan] [ 213.402178] ? __vxlan_dev_create+0x7d0/0x7d0 [vxlan] [ 213.554119] ? __netlink_ns_capable+0xc3/0xf0 [ 213.554119] __rtnl_newlink+0xb75/0x1180 [ 213.554119] ? rtnl_link_unregister+0x230/0x230 [ ... ] Fixes: 0241b836732f ("vxlan: fix default fdb entry netlink notify ordering during netdev create") Suggested-by: Roopa Prabhu Signed-off-by: Taehee Yoo --- drivers/net/vxlan.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 083f3f0bf37fd1..4066346d6f4159 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -804,6 +804,14 @@ static struct vxlan_fdb *vxlan_fdb_alloc(struct vxlan_dev *vxlan, return f; } +static void vxlan_fdb_link(struct vxlan_dev *vxlan, const u8 *mac, + __be32 src_vni, struct vxlan_fdb *f) +{ + ++vxlan->addrcnt; + hlist_add_head_rcu(&f->hlist, + vxlan_fdb_head(vxlan, mac, src_vni)); +} + static int vxlan_fdb_create(struct vxlan_dev *vxlan, const u8 *mac, union vxlan_addr *ip, __u16 state, __be16 port, __be32 src_vni, @@ -829,10 +837,6 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan, return rc; } - ++vxlan->addrcnt; - hlist_add_head_rcu(&f->hlist, - vxlan_fdb_head(vxlan, mac, src_vni)); - *fdb = f; return 0; @@ -977,6 +981,7 @@ static int vxlan_fdb_update_create(struct vxlan_dev *vxlan, if (rc < 0) return rc; + vxlan_fdb_link(vxlan, mac, src_vni, f); rc = vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH, swdev_notify, extack); if (rc) @@ -3571,12 +3576,17 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, if (err) goto errout; - /* notify default fdb entry */ if (f) { + vxlan_fdb_link(vxlan, all_zeros_mac, + vxlan->default_dst.remote_vni, f); + + /* notify default fdb entry */ err = vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH, true, extack); - if (err) - goto errout; + if (err) { + vxlan_fdb_destroy(vxlan, f, false, false); + goto unregister; + } } list_add(&vxlan->next, &vn->vxlan_list); @@ -3588,7 +3598,8 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, * destroy the entry by hand here. */ if (f) - vxlan_fdb_destroy(vxlan, f, false, false); + call_rcu(&f->rcu, vxlan_fdb_free); +unregister: if (unregister) unregister_netdevice(dev); return err;