The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7c31e54aeee517d1318dfc0bde9fa7de75893dc6 Mon Sep 17 00:00:00 2001

From: Taehee Yoo ap420073@gmail.com Date: Fri, 28 Jun 2019 14:07:25 +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_insert() is added to link fdb to vxlan dev.

vxlan_fdb_insert() 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 roopa@cumulusnetworks.com Signed-off-by: Taehee Yoo ap420073@gmail.com Acked-by: Roopa Prabhu roopa@cumulusnetworks.com Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 083f3f0bf37f..b4283f52a09d 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_insert(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, @@ -829,18 +837,13 @@ 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; }

-static void vxlan_fdb_free(struct rcu_head *head) +static void __vxlan_fdb_free(struct vxlan_fdb *f) { - struct vxlan_fdb *f = container_of(head, struct vxlan_fdb, rcu); struct vxlan_rdst *rd, *nd;

list_for_each_entry_safe(rd, nd, &f->remotes, list) { @@ -850,6 +853,13 @@ static void vxlan_fdb_free(struct rcu_head *head) kfree(f); }

+static void vxlan_fdb_free(struct rcu_head *head) +{ + struct vxlan_fdb *f = container_of(head, struct vxlan_fdb, rcu); + + __vxlan_fdb_free(f); +} + static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f, bool do_notify, bool swdev_notify) { @@ -977,6 +987,7 @@ static int vxlan_fdb_update_create(struct vxlan_dev *vxlan, if (rc < 0) return rc;

+ vxlan_fdb_insert(vxlan, mac, src_vni, f); rc = vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH, swdev_notify, extack); if (rc) @@ -3571,12 +3582,17 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, if (err) goto errout;

- /* notify default fdb entry */ if (f) { + vxlan_fdb_insert(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 +3604,8 @@ 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); + __vxlan_fdb_free(f); +unregister: if (unregister) unregister_netdevice(dev); return err;