diff mbox series

[5.2,003/313] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule

Message ID 20191003154533.875309419@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Oct. 3, 2019, 3:49 p.m. UTC 
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(-)

Comments

Jason A. Donenfeld June 23, 2020, 10:07 p.m. UTC | #1 
I realize 5.2 has long since sunsetted, and I really missed the boat
on speaking up about this many many months ago, but in case any
distros or organizations have a 5.2.x stable series, this should
probably be reverted from 5.2. The reason is that 7d9e5f422 was added
to 5.3, and introduced a UaF, which this commit then fixed. But
without 7d9e5f422, this commit adds a memory leak.

Anyway, not worth spending too much brain cycles on this, considering
5.2 isn't even mentioned on kernel.org any more, but in case it helps
for somebody doing something strange in years to come, voila.
diff mbox series

Patch

--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -285,7 +285,8 @@  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"
+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"
 
 VERBOSE=0
 PAUSE_ON_FAIL=no
@@ -582,6 +582,20 @@  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
 
@@ -1558,6 +1572,7 @@  do
 	fib_down_test|down)		fib_down_test;;
 	fib_carrier_test|carrier)	fib_carrier_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;;