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authorJuraj Sloboda <jsloboda@cisco.com>2018-10-16 12:18:21 +0200
committerDamjan Marion <dmarion@me.com>2018-10-22 12:34:49 +0000
commit68b7cb8febb2ad7123f165f9db10d3ffc3b409fe (patch)
tree9575f96b0e883a355ff4841f4707580f81e6dcb5
parent4d1a866aff6ceb03025990b6e60b42faf09ef486 (diff)
Fix buffer overflow when fragmenting packets (VPP-1383)
Change-Id: Idcda9ae55fa2efb0b2e928bac3e8e86ff8d19eba Signed-off-by: Juraj Sloboda <jsloboda@cisco.com>
-rw-r--r--src/vnet/ip/ip_frag.c5
-rw-r--r--test/test_ip4.py50
2 files changed, 53 insertions, 2 deletions
diff --git a/src/vnet/ip/ip_frag.c b/src/vnet/ip/ip_frag.c
index 628d9d66474..8de4dfc5d58 100644
--- a/src/vnet/ip/ip_frag.c
+++ b/src/vnet/ip/ip_frag.c
@@ -101,7 +101,8 @@ ip4_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
ip4 = (ip4_header_t *) vlib_buffer_get_current (from_b);
rem = clib_net_to_host_u16 (ip4->length) - sizeof (ip4_header_t);
- max = (mtu - sizeof (ip4_header_t)) & ~0x7;
+ max =
+ (clib_min (mtu, VLIB_BUFFER_DATA_SIZE) - sizeof (ip4_header_t)) & ~0x7;
if (rem >
(vlib_buffer_length_in_chain (vm, from_b) - sizeof (ip4_header_t)))
@@ -152,7 +153,7 @@ ip4_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
ip4_header_t *to_ip4;
u8 *to_data;
- len = (rem > (mtu - sizeof (ip4_header_t)) ? max : rem);
+ len = (rem > max ? max : rem);
if (len != rem) /* Last fragment does not need to divisible by 8 */
len &= ~0x7;
if ((to_b = frag_buffer_alloc (org_from_b, &to_bi)) == 0)
diff --git a/test/test_ip4.py b/test/test_ip4.py
index e9ec71a2830..ca461f1d276 100644
--- a/test/test_ip4.py
+++ b/test/test_ip4.py
@@ -1554,5 +1554,55 @@ class TestIPLPM(VppTestCase):
rx = self.send_and_expect(self.pg0, p_24 * 65, self.pg1)
+class TestIPv4Frag(VppTestCase):
+ """ IPv4 fragmentation """
+
+ @classmethod
+ def setUpClass(cls):
+ super(TestIPv4Frag, cls).setUpClass()
+
+ cls.create_pg_interfaces([0, 1])
+ cls.src_if = cls.pg0
+ cls.dst_if = cls.pg1
+
+ # setup all interfaces
+ for i in cls.pg_interfaces:
+ i.admin_up()
+ i.config_ip4()
+ i.resolve_arp()
+
+ def test_frag_large_packets(self):
+ """ Fragmentation of large packets """
+
+ p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) /
+ IP(src=self.src_if.remote_ip4, dst=self.dst_if.remote_ip4) /
+ UDP(sport=1234, dport=5678) / Raw())
+ self.extend_packet(p, 6000, "abcde")
+ saved_payload = p[Raw].load
+
+ # Force fragmentation by setting MTU of output interface
+ # lower than packet size
+ self.vapi.sw_interface_set_mtu(self.dst_if.sw_if_index,
+ [5000, 0, 0, 0])
+
+ self.pg_enable_capture()
+ self.src_if.add_stream(p)
+ self.pg_start()
+
+ # Expecting 3 fragments because size of created fragments currently
+ # cannot be larger then VPP buffer size (which is 2048)
+ packets = self.dst_if.get_capture(3)
+
+ # Assume VPP sends the fragments in order
+ payload = ''
+ for p in packets:
+ payload_offset = p.frag * 8
+ if payload_offset > 0:
+ payload_offset -= 8 # UDP header is not in payload
+ self.assert_equal(payload_offset, len(payload))
+ payload += p[Raw].load
+ self.assert_equal(payload, saved_payload, "payload")
+
+
if __name__ == '__main__':
unittest.main(testRunner=VppTestRunner)