4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rabin Vincent <rabinv@xxxxxxxx>
[ Upstream commit a2d6cbb0670d54806f18192cb0db266b4a6d285a ]
addrconf_ifdown() removes elements from the idev->addr_list without
holding the idev->lock.
If this happens while the loop in __ipv6_dev_get_saddr() is handling the
same element, that function ends up in an infinite loop:
NMI watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [test:1719]
Call Trace:
ipv6_get_saddr_eval+0x13c/0x3a0
__ipv6_dev_get_saddr+0xe4/0x1f0
ipv6_dev_get_saddr+0x1b4/0x204
ip6_dst_lookup_tail+0xcc/0x27c
ip6_dst_lookup_flow+0x38/0x80
udpv6_sendmsg+0x708/0xba8
sock_sendmsg+0x18/0x30
SyS_sendto+0xb8/0xf8
syscall_common+0x34/0x58
Fixes: 6a923934c33 (Revert "ipv6: Revert optional address flusing on ifdown.")
Signed-off-by: Rabin Vincent <rabinv@xxxxxxxx>
Acked-by: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/addrconf.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3618,14 +3618,19 @@ restart:
INIT_LIST_HEAD(&del_list);
list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list) {
struct rt6_info *rt = NULL;
+ bool keep;
addrconf_del_dad_work(ifa);
+ keep = keep_addr && (ifa->flags & IFA_F_PERMANENT) &&
+ !addr_is_local(&ifa->addr);
+ if (!keep)
+ list_move(&ifa->if_list, &del_list);
+
write_unlock_bh(&idev->lock);
spin_lock_bh(&ifa->lock);
- if (keep_addr && (ifa->flags & IFA_F_PERMANENT) &&
- !addr_is_local(&ifa->addr)) {
+ if (keep) {
/* set state to skip the notifier below */
state = INET6_IFADDR_STATE_DEAD;
ifa->state = 0;
@@ -3637,8 +3642,6 @@ restart:
} else {
state = ifa->state;
ifa->state = INET6_IFADDR_STATE_DEAD;
-
- list_move(&ifa->if_list, &del_list);
}
spin_unlock_bh(&ifa->lock);