linux-stable.git/net/mctp, branch linux-6.14.y

net: mctp: Ensure keys maintain only one ref to corresponding dev

2025-05-22T12:31:43+00:00

[ Upstream commit e4f349bd6e58051df698b82f94721f18a02a293d ]

mctp_flow_prepare_output() is called in mctp_route_output(), which
places outbound packets onto a given interface. The packet may represent
a message fragment, in which case we provoke an unbalanced reference
count to the underlying device. This causes trouble if we ever attempt
to remove the interface:

    [   48.702195] usb 1-1: USB disconnect, device number 2
    [   58.883056] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
    [   69.022548] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
    [   79.172568] unregister_netdevice: waiting for mctpusb0 to become free. Usage count = 2
    ...

Predicate the invocation of mctp_dev_set_key() in
mctp_flow_prepare_output() on not already having associated the device
with the key. It's not yet realistic to uphold the property that the key
maintains only one device reference earlier in the transmission sequence
as the route (and therefore the device) may not be known at the time the
key is associated with the socket.

Fixes: 67737c457281 ("mctp: Pass flow data & flow release events to drivers")
Acked-by: Jeremy Kerr 
Signed-off-by: Andrew Jeffery 
Link: https://patch.msgid.link/20250508-mctp-dev-refcount-v1-1-d4f965c67bb5@codeconstruct.com.au
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: mctp: Don't access ifa_index when missing

2025-05-22T12:31:43+00:00

[ Upstream commit f11cf946c0a92c560a890d68e4775723353599e1 ]

In mctp_dump_addrinfo, ifa_index can be used to filter interfaces, but
only when the struct ifaddrmsg is provided. Otherwise it will be
comparing to uninitialised memory - reproducible in the syzkaller case from
dhcpd, or busybox "ip addr show".

The kernel MCTP implementation has always filtered by ifa_index, so
existing userspace programs expecting to dump MCTP addresses must
already be passing a valid ifa_index value (either 0 or a real index).

BUG: KMSAN: uninit-value in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
 mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
 rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380
 rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824
 netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309

Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Reported-by: syzbot+e76d52dadc089b9d197f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68135815.050a0220.3a872c.000e.GAE@google.com/
Reported-by: syzbot+1065a199625a388fce60@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/681357d6.050a0220.14dd7d.000d.GAE@google.com/
Signed-off-by: Matt Johnston 
Link: https://patch.msgid.link/20250508-mctp-addr-dump-v2-1-c8a53fd2dd66@codeconstruct.com.au
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: mctp: Set SOCK_RCU_FREE

2025-04-25T08:50:52+00:00

[ Upstream commit 52024cd6ec71a6ca934d0cc12452bd8d49850679 ]

Bind lookup runs under RCU, so ensure that a socket doesn't go away in
the middle of a lookup.

Fixes: 833ef3b91de6 ("mctp: Populate socket implementation")
Signed-off-by: Matt Johnston 
Link: https://patch.msgid.link/20250410-mctp-rcu-sock-v1-1-872de9fdc877@codeconstruct.com.au
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: mctp: unshare packets when reassembling

2025-03-11T12:12:19+00:00

Ensure that the frag_list used for reassembly isn't shared with other
packets. This avoids incorrect reassembly when packets are cloned, and
prevents a memory leak due to circular references between fragments and
their skb_shared_info.

The upcoming MCTP-over-USB driver uses skb_clone which can trigger the
problem - other MCTP drivers don't share SKBs.

A kunit test is added to reproduce the issue.

Signed-off-by: Matt Johnston 
Fixes: 4a992bbd3650 ("mctp: Implement message fragmentation & reassembly")
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20250306-matt-mctp-usb-v1-1-085502b3dd28@codeconstruct.com.au
Signed-off-by: Paolo Abeni

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2024-12-19T19:35:07+00:00

Cross-merge networking fixes after downstream PR (net-6.13-rc4).

No conflicts.

Adjacent changes:

drivers/net/ethernet/renesas/rswitch.h
  32fd46f5b69e ("net: renesas: rswitch: remove speed from gwca structure")
  922b4b955a03 ("net: renesas: rswitch: rework ts tags management")

Signed-off-by: Jakub Kicinski

net: mctp: handle skb cleanup on sock_queue failures

2024-12-19T10:52:49+00:00

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@vger.kernel.org
Signed-off-by: Jeremy Kerr 
Link: https://patch.msgid.link/20241218-mctp-next-v2-1-1c1729645eaa@codeconstruct.com.au
Signed-off-by: Paolo Abeni

mctp: no longer rely on net->dev_index_head[]

2024-12-09T22:29:14+00:00

mctp_dump_addrinfo() is one of the last users of
net->dev_index_head[] in the control path.

Switch to for_each_netdev_dump() for better scalability.

Use C99 for mctp_device_rtnl_msg_handlers[] to prepare
future RTNL removal from mctp_dump_addrinfo()

(mdev->addrs is not yet RCU protected)

Signed-off-by: Eric Dumazet 
Cc: Matt Johnston 
Reviewed-by: Kuniyuki Iwashima 
Acked-by: Jeremy Kerr 
Link: https://patch.msgid.link/20241206223811.1343076-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

net: mctp: Expose transport binding identifier via IFLA attribute

2024-11-09T17:04:54+00:00

MCTP control protocol implementations are transport binding dependent.
Endpoint discovery is mandatory based on transport binding.
Message timing requirements are specified in each respective transport
binding specification.

However, we currently have no means to get this information from MCTP
links.

Add a IFLA_MCTP_PHYS_BINDING netlink link attribute, which represents
the transport type using the DMTF DSP0239-defined type numbers, returned
as part of RTM_GETLINK data.

We get an IFLA_MCTP_PHYS_BINDING attribute for each MCTP link, for
example:

- 0x00 (unspec) for loopback interface;
- 0x01 (SMBus/I2C) for mctpi2c%d interfaces; and
- 0x05 (serial) for mctpserial%d interfaces.

Signed-off-by: Khang Nguyen 
Reviewed-by: Matt Johnston 
Link: https://patch.msgid.link/20241105071915.821871-1-khangng@os.amperecomputing.com
Signed-off-by: Jakub Kicinski

rtnetlink: Return int from rtnl_af_register().

2024-10-22T09:02:05+00:00

The next patch will add init_srcu_struct() in rtnl_af_register(),
then we need to handle its error.

Let's add the error handling in advance to make the following
patch cleaner.

Signed-off-by: Kuniyuki Iwashima 
Reviewed-by: Matt Johnston 
Signed-off-by: Paolo Abeni

mctp: Handle error of rtnl_register_module().

2024-10-10T13:39:35+00:00

Since introduced, mctp has been ignoring the returned value of
rtnl_register_module(), which could fail silently.

Handling the error allows users to view a module as an all-or-nothing
thing in terms of the rtnetlink functionality.  This prevents syzkaller
from reporting spurious errors from its tests, where OOM often occurs
and module is automatically loaded.

Let's handle the errors by rtnl_register_many().

Fixes: 583be982d934 ("mctp: Add device handling and netlink interface")
Fixes: 831119f88781 ("mctp: Add neighbour netlink interface")
Fixes: 06d2f4c583a7 ("mctp: Add netlink route management")
Signed-off-by: Kuniyuki Iwashima 
Reviewed-by: Jeremy Kerr 
Signed-off-by: Paolo Abeni