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Subject[PATCH 5.3 003/344] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule
Date
From: "Jason A. Donenfeld" <Jason@zx2c4.com>

[ Upstream commit ca7a03c4175366a92cee0ccc4fec0038c3266e26 ]

Commit 7d9e5f422150 removed references from certain dsts, but accounting
for this never translated down into the fib6 suppression code. This bug
was triggered by WireGuard users who use wg-quick(8), which uses the
"suppress-prefix" directive to ip-rule(8) for routing all of their
internet traffic without routing loops. The test case added here
causes the reference underflow by causing packets to evaluate a suppress
rule.

Fixes: 7d9e5f422150 ("ipv6: convert major tx path to use RT6_LOOKUP_F_DST_NOREF")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/fib6_rules.c | 3 ++-
tools/testing/selftests/net/fib_tests.sh | 17 ++++++++++++++++-
2 files changed, 18 insertions(+), 2 deletions(-)

--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -287,7 +287,8 @@ static bool fib6_rule_suppress(struct fi
return false;

suppress_route:
- ip6_rt_put(rt);
+ if (!(arg->flags & FIB_LOOKUP_NOREF))
+ ip6_rt_put(rt);
return true;
}

--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -9,7 +9,7 @@ ret=0
ksft_skip=4

# all tests in this script. Can be overridden with -t option
-TESTS="unregister down carrier nexthop ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw rp_filter"
+TESTS="unregister down carrier nexthop suppress ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw rp_filter"

VERBOSE=0
PAUSE_ON_FAIL=no
@@ -614,6 +614,20 @@ fib_nexthop_test()
cleanup
}

+fib_suppress_test()
+{
+ $IP link add dummy1 type dummy
+ $IP link set dummy1 up
+ $IP -6 route add default dev dummy1
+ $IP -6 rule add table main suppress_prefixlength 0
+ ping -f -c 1000 -W 1 1234::1 || true
+ $IP -6 rule del table main suppress_prefixlength 0
+ $IP link del dummy1
+
+ # If we got here without crashing, we're good.
+ return 0
+}
+
################################################################################
# Tests on route add and replace

@@ -1591,6 +1605,7 @@ do
fib_carrier_test|carrier) fib_carrier_test;;
fib_rp_filter_test|rp_filter) fib_rp_filter_test;;
fib_nexthop_test|nexthop) fib_nexthop_test;;
+ fib_suppress_test|suppress) fib_suppress_test;;
ipv6_route_test|ipv6_rt) ipv6_route_test;;
ipv4_route_test|ipv4_rt) ipv4_route_test;;
ipv6_addr_metric) ipv6_addr_metric_test;;

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