6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jeremy Kerr <jk@xxxxxxxxxxxxxxxxxxxx>
commit ce1219c3f76bb131d095e90521506d3c6ccfa086 upstream.
Currently, we don't use the return value from sock_queue_rcv_skb, which
means we may leak skbs if a message is not successfully queued to a
socket.
Instead, ensure that we're freeing the skb where the sock hasn't
otherwise taken ownership of the skb by adding checks on the
sock_queue_rcv_skb() to invoke a kfree on failure.
In doing so, rather than using the 'rc' value to trigger the
kfree_skb(), use the skb pointer itself, which is more explicit.
Also, add a kunit test for the sock delivery failure cases.
Fixes: 4a992bbd3650 ("mctp: Implement message fragmentation & reassembly")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeremy Kerr <jk@xxxxxxxxxxxxxxxxxxxx>
Link: https://patch.msgid.link/20241218-mctp-next-v2-1-1c1729645eaa@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mctp/route.c | 36 +++++++++++++-----
net/mctp/test/route-test.c | 86 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+), 10 deletions(-)
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -374,8 +374,13 @@ static int mctp_route_input(struct mctp_
msk = NULL;
rc = -EINVAL;
- /* we may be receiving a locally-routed packet; drop source sk
- * accounting
+ /* We may be receiving a locally-routed packet; drop source sk
+ * accounting.
+ *
+ * From here, we will either queue the skb - either to a frag_queue, or
+ * to a receiving socket. When that succeeds, we clear the skb pointer;
+ * a non-NULL skb on exit will be otherwise unowned, and hence
+ * kfree_skb()-ed.
*/
skb_orphan(skb);
@@ -434,7 +439,9 @@ static int mctp_route_input(struct mctp_
* pending key.
*/
if (flags & MCTP_HDR_FLAG_EOM) {
- sock_queue_rcv_skb(&msk->sk, skb);
+ rc = sock_queue_rcv_skb(&msk->sk, skb);
+ if (!rc)
+ skb = NULL;
if (key) {
/* we've hit a pending reassembly; not much we
* can do but drop it
@@ -443,7 +450,6 @@ static int mctp_route_input(struct mctp_
MCTP_TRACE_KEY_REPLIED);
key = NULL;
}
- rc = 0;
goto out_unlock;
}
@@ -470,8 +476,10 @@ static int mctp_route_input(struct mctp_
* this function.
*/
rc = mctp_key_add(key, msk);
- if (!rc)
+ if (!rc) {
trace_mctp_key_acquire(key);
+ skb = NULL;
+ }
/* we don't need to release key->lock on exit, so
* clean up here and suppress the unlock via
@@ -489,6 +497,8 @@ static int mctp_route_input(struct mctp_
key = NULL;
} else {
rc = mctp_frag_queue(key, skb);
+ if (!rc)
+ skb = NULL;
}
}
@@ -503,12 +513,19 @@ static int mctp_route_input(struct mctp_
else
rc = mctp_frag_queue(key, skb);
+ if (rc)
+ goto out_unlock;
+
+ /* we've queued; the queue owns the skb now */
+ skb = NULL;
+
/* end of message? deliver to socket, and we're done with
* the reassembly/response key
*/
- if (!rc && flags & MCTP_HDR_FLAG_EOM) {
- sock_queue_rcv_skb(key->sk, key->reasm_head);
- key->reasm_head = NULL;
+ if (flags & MCTP_HDR_FLAG_EOM) {
+ rc = sock_queue_rcv_skb(key->sk, key->reasm_head);
+ if (!rc)
+ key->reasm_head = NULL;
__mctp_key_done_in(key, net, f, MCTP_TRACE_KEY_REPLIED);
key = NULL;
}
@@ -527,8 +544,7 @@ out_unlock:
if (any_key)
mctp_key_unref(any_key);
out:
- if (rc)
- kfree_skb(skb);
+ kfree_skb(skb);
return rc;
}
--- a/net/mctp/test/route-test.c
+++ b/net/mctp/test/route-test.c
@@ -837,6 +837,90 @@ static void mctp_test_route_input_multip
mctp_test_route_input_multiple_nets_key_fini(test, &t2);
}
+/* Input route to socket, using a single-packet message, where sock delivery
+ * fails. Ensure we're handling the failure appropriately.
+ */
+static void mctp_test_route_input_sk_fail_single(struct kunit *test)
+{
+ const struct mctp_hdr hdr = RX_HDR(1, 10, 8, FL_S | FL_E | FL_TO);
+ struct mctp_test_route *rt;
+ struct mctp_test_dev *dev;
+ struct socket *sock;
+ struct sk_buff *skb;
+ int rc;
+
+ __mctp_route_test_init(test, &dev, &rt, &sock, MCTP_NET_ANY);
+
+ /* No rcvbuf space, so delivery should fail. __sock_set_rcvbuf will
+ * clamp the minimum to SOCK_MIN_RCVBUF, so we open-code this.
+ */
+ lock_sock(sock->sk);
+ WRITE_ONCE(sock->sk->sk_rcvbuf, 0);
+ release_sock(sock->sk);
+
+ skb = mctp_test_create_skb(&hdr, 10);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, skb);
+ skb_get(skb);
+
+ mctp_test_skb_set_dev(skb, dev);
+
+ /* do route input, which should fail */
+ rc = mctp_route_input(&rt->rt, skb);
+ KUNIT_EXPECT_NE(test, rc, 0);
+
+ /* we should hold the only reference to skb */
+ KUNIT_EXPECT_EQ(test, refcount_read(&skb->users), 1);
+ kfree_skb(skb);
+
+ __mctp_route_test_fini(test, dev, rt, sock);
+}
+
+/* Input route to socket, using a fragmented message, where sock delivery fails.
+ */
+static void mctp_test_route_input_sk_fail_frag(struct kunit *test)
+{
+ const struct mctp_hdr hdrs[2] = { RX_FRAG(FL_S, 0), RX_FRAG(FL_E, 1) };
+ struct mctp_test_route *rt;
+ struct mctp_test_dev *dev;
+ struct sk_buff *skbs[2];
+ struct socket *sock;
+ unsigned int i;
+ int rc;
+
+ __mctp_route_test_init(test, &dev, &rt, &sock, MCTP_NET_ANY);
+
+ lock_sock(sock->sk);
+ WRITE_ONCE(sock->sk->sk_rcvbuf, 0);
+ release_sock(sock->sk);
+
+ for (i = 0; i < ARRAY_SIZE(skbs); i++) {
+ skbs[i] = mctp_test_create_skb(&hdrs[i], 10);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, skbs[i]);
+ skb_get(skbs[i]);
+
+ mctp_test_skb_set_dev(skbs[i], dev);
+ }
+
+ /* first route input should succeed, we're only queueing to the
+ * frag list
+ */
+ rc = mctp_route_input(&rt->rt, skbs[0]);
+ KUNIT_EXPECT_EQ(test, rc, 0);
+
+ /* final route input should fail to deliver to the socket */
+ rc = mctp_route_input(&rt->rt, skbs[1]);
+ KUNIT_EXPECT_NE(test, rc, 0);
+
+ /* we should hold the only reference to both skbs */
+ KUNIT_EXPECT_EQ(test, refcount_read(&skbs[0]->users), 1);
+ kfree_skb(skbs[0]);
+
+ KUNIT_EXPECT_EQ(test, refcount_read(&skbs[1]->users), 1);
+ kfree_skb(skbs[1]);
+
+ __mctp_route_test_fini(test, dev, rt, sock);
+}
+
#if IS_ENABLED(CONFIG_MCTP_FLOWS)
static void mctp_test_flow_init(struct kunit *test,
@@ -1053,6 +1137,8 @@ static struct kunit_case mctp_test_cases
mctp_route_input_sk_reasm_gen_params),
KUNIT_CASE_PARAM(mctp_test_route_input_sk_keys,
mctp_route_input_sk_keys_gen_params),
+ KUNIT_CASE(mctp_test_route_input_sk_fail_single),
+ KUNIT_CASE(mctp_test_route_input_sk_fail_frag),
KUNIT_CASE(mctp_test_route_input_multiple_nets_bind),
KUNIT_CASE(mctp_test_route_input_multiple_nets_key),
KUNIT_CASE(mctp_test_packet_flow),
