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net: mctp: handle skb cleanup on sock_queue failures

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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: 4a992bbd36 ("mctp: Implement message fragmentation & reassembly")
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://patch.msgid.link/20241218-mctp-next-v2-1-1c1729645eaa@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jeremy Kerr 2024-12-18 11:53:01 +08:00 committed by Paolo Abeni
parent 572af9f284
commit ce1219c3f7
2 changed files with 112 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
net/mctp/route.c
View File

@ -374,8 +374,13 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
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_route *route, struct sk_buff *skb)
* 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_route *route, struct sk_buff *skb)
MCTP_TRACE_KEY_REPLIED);
key = NULL;
}
rc = 0;
goto out_unlock;
}
@ -470,8 +476,10 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
* 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_route *route, struct sk_buff *skb)
key = NULL;
} else {
rc = mctp_frag_queue(key, skb);
if (!rc)
skb = NULL;
}
}
@ -503,12 +513,19 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
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 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
if (any_key)
mctp_key_unref(any_key);
out:
if (rc)
kfree_skb(skb);
kfree_skb(skb);
return rc;
}

86
net/mctp/test/route-test.c
View File

@ -837,6 +837,90 @@ static void mctp_test_route_input_multiple_nets_key(struct kunit *test)
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),