From: David Ahern <dsahern@xxxxxxxxx>
[ Upstream commit 7c74b0bec918c1e0ca0b4208038c156eacf8f13f ]
A user reported [0] hitting the WARN_ON in fib_info_nh:
[ 8633.839816] ------------[ cut here ]------------
[ 8633.839819] WARNING: CPU: 0 PID: 1719 at include/net/nexthop.h:251 fib_select_path+0x303/0x381
...
[ 8633.839846] RIP: 0010:fib_select_path+0x303/0x381
...
[ 8633.839848] RSP: 0018:ffffb04d407f7d00 EFLAGS: 00010286
[ 8633.839850] RAX: 0000000000000000 RBX: ffff9460b9897ee8 RCX: 00000000000000fe
[ 8633.839851] RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000
[ 8633.839852] RBP: ffff946076049850 R08: 0000000059263a83 R09: ffff9460840e4000
[ 8633.839853] R10: 0000000000000014 R11: 0000000000000000 R12: ffffb04d407f7dc0
[ 8633.839854] R13: ffffffffa4ce3240 R14: 0000000000000000 R15: ffff9460b7681f60
[ 8633.839857] FS: 00007fcac2e02700(0000) GS:ffff9460bdc00000(0000) knlGS:0000000000000000
[ 8633.839858] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8633.839859] CR2: 00007f27beb77e28 CR3: 0000000077734000 CR4: 00000000000006f0
[ 8633.839867] Call Trace:
[ 8633.839871] ip_route_output_key_hash_rcu+0x421/0x890
[ 8633.839873] ip_route_output_key_hash+0x5e/0x80
[ 8633.839876] ip_route_output_flow+0x1a/0x50
[ 8633.839878] __ip4_datagram_connect+0x154/0x310
[ 8633.839880] ip4_datagram_connect+0x28/0x40
[ 8633.839882] __sys_connect+0xd6/0x100
...
The WARN_ON is triggered in fib_select_default which is invoked when
there are multiple default routes. Update the function to use
fib_info_nhc and convert the nexthop checks to use fib_nh_common.
Add test case that covers the affected code path.
[0] https://github.com/FRRouting/frr/issues/6089
Fixes: 493ced1ac47c ("ipv4: Allow routes to use nexthop objects")
Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/fib_semantics.c | 6 +++---
tools/testing/selftests/net/fib_nexthops.sh | 23 +++++++++++++++++++++++
2 files changed, 26 insertions(+), 3 deletions(-)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -2012,7 +2012,7 @@ static void fib_select_default(const str
hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
struct fib_info *next_fi = fa->fa_info;
- struct fib_nh *nh;
+ struct fib_nh_common *nhc;
if (fa->fa_slen != slen)
continue;
@@ -2035,8 +2035,8 @@ static void fib_select_default(const str
fa->fa_type != RTN_UNICAST)
continue;
- nh = fib_info_nh(next_fi, 0);
- if (!nh->fib_nh_gw4 || nh->fib_nh_scope != RT_SCOPE_LINK)
+ nhc = fib_info_nhc(next_fi, 0);
+ if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
continue;
fib_alias_accessed(fa);
--- a/tools/testing/selftests/net/fib_nexthops.sh
+++ b/tools/testing/selftests/net/fib_nexthops.sh
@@ -749,6 +749,29 @@ ipv4_fcnal_runtime()
run_cmd "ip netns exec me ping -c1 -w1 172.16.101.1"
log_test $? 0 "Ping - multipath"
+ run_cmd "$IP ro delete 172.16.101.1/32 nhid 122"
+
+ #
+ # multiple default routes
+ # - tests fib_select_default
+ run_cmd "$IP nexthop add id 501 via 172.16.1.2 dev veth1"
+ run_cmd "$IP ro add default nhid 501"
+ run_cmd "$IP ro add default via 172.16.1.3 dev veth1 metric 20"
+ run_cmd "ip netns exec me ping -c1 -w1 172.16.101.1"
+ log_test $? 0 "Ping - multiple default routes, nh first"
+
+ # flip the order
+ run_cmd "$IP ro del default nhid 501"
+ run_cmd "$IP ro del default via 172.16.1.3 dev veth1 metric 20"
+ run_cmd "$IP ro add default via 172.16.1.2 dev veth1 metric 20"
+ run_cmd "$IP nexthop replace id 501 via 172.16.1.3 dev veth1"
+ run_cmd "$IP ro add default nhid 501 metric 20"
+ run_cmd "ip netns exec me ping -c1 -w1 172.16.101.1"
+ log_test $? 0 "Ping - multiple default routes, nh second"
+
+ run_cmd "$IP nexthop delete nhid 501"
+ run_cmd "$IP ro del default"
+
#
# IPv4 with blackhole nexthops
#
