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authorNiels Dossche <dossche.niels@gmail.com>2022-04-04 01:15:24 +0200
committerJakub Kicinski <kuba@kernel.org>2022-04-06 22:09:39 -0700
commit51454ea42c1ab4e0c2828bb0d4d53957976980de (patch)
tree8cc0f333a50eed09b36ab035d77a3eab4069ea64 /net/ipv6
parent8dd7cdb0f473407fdcd231c3eccef07371fd5e58 (diff)
ipv6: fix locking issues with loops over idev->addr_list
idev->addr_list needs to be protected by idev->lock. However, it is not always possible to do so while iterating and performing actions on inet6_ifaddr instances. For example, multiple functions (like addrconf_{join,leave}_anycast) eventually call down to other functions that acquire the idev->lock. The current code temporarily unlocked the idev->lock during the loops, which can cause race conditions. Moving the locks up is also not an appropriate solution as the ordering of lock acquisition will be inconsistent with for example mc_lock. This solution adds an additional field to inet6_ifaddr that is used to temporarily add the instances to a temporary list while holding idev->lock. The temporary list can then be traversed without holding idev->lock. This change was done in two places. In addrconf_ifdown, the list_for_each_entry_safe variant of the list loop is also no longer necessary as there is no deletion within that specific loop. Suggested-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Niels Dossche <dossche.niels@gmail.com> Acked-by: Paolo Abeni <pabeni@redhat.com> Link: https://lore.kernel.org/r/20220403231523.45843-1-dossche.niels@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/addrconf.c30
1 files changed, 24 insertions, 6 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index b22504176588..1afc4c024981 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -797,6 +797,7 @@ static void dev_forward_change(struct inet6_dev *idev)
{
struct net_device *dev;
struct inet6_ifaddr *ifa;
+ LIST_HEAD(tmp_addr_list);
if (!idev)
return;
@@ -815,14 +816,24 @@ static void dev_forward_change(struct inet6_dev *idev)
}
}
+ read_lock_bh(&idev->lock);
list_for_each_entry(ifa, &idev->addr_list, if_list) {
if (ifa->flags&IFA_F_TENTATIVE)
continue;
+ list_add_tail(&ifa->if_list_aux, &tmp_addr_list);
+ }
+ read_unlock_bh(&idev->lock);
+
+ while (!list_empty(&tmp_addr_list)) {
+ ifa = list_first_entry(&tmp_addr_list,
+ struct inet6_ifaddr, if_list_aux);
+ list_del(&ifa->if_list_aux);
if (idev->cnf.forwarding)
addrconf_join_anycast(ifa);
else
addrconf_leave_anycast(ifa);
}
+
inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
NETCONFA_FORWARDING,
dev->ifindex, &idev->cnf);
@@ -3728,7 +3739,8 @@ static int addrconf_ifdown(struct net_device *dev, bool unregister)
unsigned long event = unregister ? NETDEV_UNREGISTER : NETDEV_DOWN;
struct net *net = dev_net(dev);
struct inet6_dev *idev;
- struct inet6_ifaddr *ifa, *tmp;
+ struct inet6_ifaddr *ifa;
+ LIST_HEAD(tmp_addr_list);
bool keep_addr = false;
bool was_ready;
int state, i;
@@ -3820,16 +3832,23 @@ restart:
write_lock_bh(&idev->lock);
}
- list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list) {
+ list_for_each_entry(ifa, &idev->addr_list, if_list)
+ list_add_tail(&ifa->if_list_aux, &tmp_addr_list);
+ write_unlock_bh(&idev->lock);
+
+ while (!list_empty(&tmp_addr_list)) {
struct fib6_info *rt = NULL;
bool keep;
+ ifa = list_first_entry(&tmp_addr_list,
+ struct inet6_ifaddr, if_list_aux);
+ list_del(&ifa->if_list_aux);
+
addrconf_del_dad_work(ifa);
keep = keep_addr && (ifa->flags & IFA_F_PERMANENT) &&
!addr_is_local(&ifa->addr);
- write_unlock_bh(&idev->lock);
spin_lock_bh(&ifa->lock);
if (keep) {
@@ -3860,15 +3879,14 @@ restart:
addrconf_leave_solict(ifa->idev, &ifa->addr);
}
- write_lock_bh(&idev->lock);
if (!keep) {
+ write_lock_bh(&idev->lock);
list_del_rcu(&ifa->if_list);
+ write_unlock_bh(&idev->lock);
in6_ifa_put(ifa);
}
}
- write_unlock_bh(&idev->lock);
-
/* Step 5: Discard anycast and multicast list */
if (unregister) {
ipv6_ac_destroy_dev(idev);