[PATCH 5.4 046/155] hsr: use rcu_read_lock() in hsr_get_node_{list/status}()

Greg Kroah-Hartman
2020-03-31T09:13:02Z

From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit 173756b86803655d70af7732079b3aa935e6ab68 ]

hsr_get_node_{list/status}() are not under rtnl_lock() because
they are callback functions of generic netlink.
But they use __dev_get_by_index() without rtnl_lock().
So, it would use unsafe data.
In order to fix it, rcu_read_lock() and dev_get_by_index_rcu()
are used instead of __dev_get_by_index().

Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/hsr/hsr_framereg.c | 9 ++-------
net/hsr/hsr_netlink.c | 39 +++++++++++++++++++++------------------
2 files changed, 23 insertions(+), 25 deletions(-)

--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -482,12 +482,9 @@ int hsr_get_node_data(struct hsr_priv *h
struct hsr_port *port;
unsigned long tdiff;

- rcu_read_lock();
node = find_node_by_addr_A(&hsr->node_db, addr);
- if (!node) {
- rcu_read_unlock();
- return -ENOENT; /* No such entry */
- }
+ if (!node)
+ return -ENOENT;

ether_addr_copy(addr_b, node->macaddress_B);

@@ -522,7 +519,5 @@ int hsr_get_node_data(struct hsr_priv *h
*addr_b_ifindex = -1;
}

- rcu_read_unlock();
-
return 0;
}
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -251,15 +251,16 @@ static int hsr_get_node_status(struct sk
if (!na)
goto invalid;

- hsr_dev = __dev_get_by_index(genl_info_net(info),
- nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+ rcu_read_lock();
+ hsr_dev = dev_get_by_index_rcu(genl_info_net(info),
+ nla_get_u32(info->attrs[HSR_A_IFINDEX]));
if (!hsr_dev)
- goto invalid;
+ goto rcu_unlock;
if (!is_hsr_master(hsr_dev))
- goto invalid;
+ goto rcu_unlock;

/* Send reply */
- skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+ skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
if (!skb_out) {
res = -ENOMEM;
goto fail;
@@ -313,12 +314,10 @@ static int hsr_get_node_status(struct sk
res = nla_put_u16(skb_out, HSR_A_IF1_SEQ, hsr_node_if1_seq);
if (res < 0)
goto nla_put_failure;
- rcu_read_lock();
port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
if (port)
res = nla_put_u32(skb_out, HSR_A_IF1_IFINDEX,
port->dev->ifindex);
- rcu_read_unlock();
if (res < 0)
goto nla_put_failure;

@@ -328,20 +327,22 @@ static int hsr_get_node_status(struct sk
res = nla_put_u16(skb_out, HSR_A_IF2_SEQ, hsr_node_if2_seq);
if (res < 0)
goto nla_put_failure;
- rcu_read_lock();
port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
if (port)
res = nla_put_u32(skb_out, HSR_A_IF2_IFINDEX,
port->dev->ifindex);
- rcu_read_unlock();
if (res < 0)
goto nla_put_failure;

+ rcu_read_unlock();
+
genlmsg_end(skb_out, msg_head);
genlmsg_unicast(genl_info_net(info), skb_out, info->snd_portid);

return 0;

+rcu_unlock:
+ rcu_read_unlock();
invalid:
netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL, NULL);
return 0;
@@ -351,6 +352,7 @@ nla_put_failure:
/* Fall through */

fail:
+ rcu_read_unlock();
return res;
}

@@ -377,15 +379,16 @@ static int hsr_get_node_list(struct sk_b
if (!na)
goto invalid;

- hsr_dev = __dev_get_by_index(genl_info_net(info),
- nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+ rcu_read_lock();
+ hsr_dev = dev_get_by_index_rcu(genl_info_net(info),
+ nla_get_u32(info->attrs[HSR_A_IFINDEX]));
if (!hsr_dev)
- goto invalid;
+ goto rcu_unlock;
if (!is_hsr_master(hsr_dev))
- goto invalid;
+ goto rcu_unlock;

/* Send reply */
- skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+ skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
if (!skb_out) {
res = -ENOMEM;
goto fail;
@@ -405,14 +408,11 @@ static int hsr_get_node_list(struct sk_b

hsr = netdev_priv(hsr_dev);

- rcu_read_lock();
pos = hsr_get_next_node(hsr, NULL, addr);
while (pos) {
res = nla_put(skb_out, HSR_A_NODE_ADDR, ETH_ALEN, addr);
- if (res < 0) {
- rcu_read_unlock();
+ if (res < 0)
goto nla_put_failure;
- }
pos = hsr_get_next_node(hsr, pos, addr);
}
rcu_read_unlock();
@@ -422,6 +422,8 @@ static int hsr_get_node_list(struct sk_b

return 0;

+rcu_unlock:
+ rcu_read_unlock();
invalid:
netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL, NULL);
return 0;
@@ -431,6 +433,7 @@ nla_put_failure:
/* Fall through */

fail:
+ rcu_read_unlock();
return res;
}