linux-stable.git/drivers/net/netdevsim, branch master

netdevsim: tc: allow to test nf_tables offload control plane code

2026-06-13T17:29:39+00:00

The actual 'offload' is phony, all commands are ignored: this is only
useful to test control plane code.

Tag the existing callback to permit error injection to test rollback/abort
code in nf_tables.  This is also for fuzzers - the fault injection
framework allows probabilistic error insertion.

Signed-off-by: Florian Westphal 
Link: https://patch.msgid.link/20260612092209.11966-2-fw@strlen.de
Signed-off-by: Jakub Kicinski

net: change ndo_set_rx_mode_async return type to int

2026-06-10T01:15:29+00:00

Change the return type of ndo_set_rx_mode_async from void to int to
allow drivers to report failures back to the core stack. This is a
prerequisite for adding retry logic in the core when drivers fail to
program RX filters (e.g. bnxt VF when PF is unavailable).

All existing implementations return 0 for now, maintaining current
behavior.

Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20260608154014.227538-2-sdf@fomichev.me
Signed-off-by: Jakub Kicinski

net: ethtool: optionally skip rtnl_lock on Netlink path for SET ops

2026-06-09T17:13:05+00:00

Make ethtool not take rtnl_lock for SET commands when operation
is performed on an ops-locked driver. cfg/cfg_pending are now
ops-locked, since only ethtool modifies them.

Some SET driver callbacks will still need rtnl_lock, most notably
those which may end up calling netdev_update_features() or the qdisc
layer (via netif_set_real_num_tx_queues()). Let drivers selectively
opt back into the rtnl_lock with a new bitfield in ops.

We need two helpers since Netlink and ioctl cmds have different
values. Keep the helpers side by side in common.h to make sure
they get updated together, even tho they will only get called
from ioctl.c and netlink.c.

SET commands which don't use ethnl_default_set_doit() are converted
by subsequent commits.

Reviewed-by: Eric Dumazet 
Acked-by: Stanislav Fomichev 
Reviewed-by: Jacob Keller 
Link: https://patch.msgid.link/20260605002912.3456868-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski

netdevsim: psp: use atomic64 for psp stats counters

2026-06-02T19:57:46+00:00

The existing u64_stats_t-based psp counters had two preexisting api
usage bugs: u64_stats_init() was never called on the syncp object, and
the writer side of the u64_stats_update_begin()/end() api was not
serialized. Switch the counters to atomic64_t instead. Atomics need
no initialization and are inherently safe against concurrent writers,
eliminating both bugs at once.

Use atomic64_t rather than atomic_long_t so byte counters don't wrap
at 4 GiB on 32-bit builds.

Fixes: 178f0763c5f3 ("netdevsim: implement psp device stats")
Cc:  # netdevsim is a test harness, it's never loaded on production systems
Signed-off-by: Daniel Zahka 
Link: https://patch.msgid.link/20260529-fix-psp-stats-v2-2-3a194eacf18e@gmail.com
Signed-off-by: Jakub Kicinski

netdevsim: psp: update rx stats on the peer netdevsim

2026-06-02T19:57:30+00:00

nsim_do_psp() handles both tx and rx psp processing in the sending
device's nsim_start_xmit() path. The existing code has a logical bug,
where we erroneously increment rx_bytes and rx_packets on the sending
devices stats, instead of the peer device.

Additionally, compute psp_len after psp_dev_encapsulate() and before
psp_dev_rcv(), which modifies the header region of the skb. The
existing calculation was actually correct, because psp_dev_rcv()
leaves skb_inner_transport_header pointing at the tcp header, but this
is fragile and confusing as there is no actual inner transport header
after psp_dev_rcv has removed udp encapsulation.

Fixes: 178f0763c5f3 ("netdevsim: implement psp device stats")
Cc:  # netdevsim is a test harness, it's never loaded on production systems
Signed-off-by: Daniel Zahka 
Link: https://patch.msgid.link/20260529-fix-psp-stats-v2-1-3a194eacf18e@gmail.com
Signed-off-by: Jakub Kicinski

netdevsim: fib: fix use-after-free of FIB data via debugfs

2026-06-02T19:54:58+00:00

Writing to the netdevsim debugfs file
"netdevsim/netdevsimN/fib/nexthop_bucket_activity" enters
nsim_nexthop_bucket_activity_write(), which looks up a nexthop in
data->nexthop_ht under rtnl_lock(). If a network namespace teardown,
devlink reload or device deletion runs concurrently, nsim_fib_destroy()
frees that rhashtable (and the surrounding nsim_fib_data) while the
write is still in flight, leading to a slab-use-after-free:

  BUG: KASAN: slab-use-after-free in nsim_nexthop_bucket_activity_write+0xb9e/0xdf0
  Read of size 4 at addr ff1100001a379808 by task syz.0.11967/27894

  CPU: 0 UID: 0 PID: 27894 Comm: syz.0.11967 Not tainted 7.1.0-rc4-gf6f1bfc1980a #4
  Call Trace:
   nsim_nexthop_bucket_activity_write+0xb9e/0xdf0
   full_proxy_write+0x135/0x1a0
   vfs_write+0x2e2/0x1040
   ksys_write+0x146/0x270
   __x64_sys_write+0x76/0xb0
   do_syscall_64+0xb9/0x5b0
   entry_SYSCALL_64_after_hwframe+0x74/0x7c

  Allocated by task 15957:
   rhashtable_init_noprof+0x3ec/0x860
   nsim_fib_create+0x371/0xca0
   nsim_drv_probe+0xd60/0x15c0
   ...
   new_device_store+0x425/0x7f0

  Freed by task 24:
   rhashtable_free_and_destroy+0x10d/0x620
   nsim_fib_destroy+0xc9/0x1c0
   nsim_dev_reload_destroy+0x1e7/0x530
   nsim_dev_reload_down+0x6b/0xd0
   devlink_reload+0x1b5/0x770
   devlink_pernet_pre_exit+0x25d/0x3a0
   ops_undo_list+0x1b7/0xb90
   cleanup_net+0x47f/0x8a0

  The buggy address belongs to the object at ff1100001a379800
   which belongs to the cache kmalloc-1k of size 1024

The freed 1k object is the bucket table of data->nexthop_ht. Shortly
after, the dangling table is dereferenced again and the machine also
takes a GPF in __rht_bucket_nested() from the same call site.

The root cause is a lifetime mismatch: the debugfs files reference
nsim_fib_data (the writer dereferences data->nexthop_ht), but the
interface is not bracketed around the lifetime of that data.
nsim_fib_destroy() freed both rhashtables and only removed the debugfs
directory afterwards, and nsim_fib_create() created the debugfs files
before the rhashtables were initialized and, on the error path, freed
them before removing the files. debugfs keeps the file itself alive
across a ->write() via debugfs_file_get()/debugfs_file_put()
(fs/debugfs/file.c), but it does not keep data->nexthop_ht alive, so the
in-flight writer dereferenced freed memory. rtnl_lock() in the writer
does not help, because the teardown path does not take rtnl around
rhashtable_free_and_destroy().

Fix it by bracketing the debugfs interface around the data it exposes,
keeping nsim_fib_create() and nsim_fib_destroy() symmetric:

 - In nsim_fib_destroy(), tear down the debugfs files before the data
   structures they reference. debugfs_remove_recursive() drops the
   initial active-user reference and then waits for every in-flight
   ->write() to drop its reference before returning, and rejects new
   opens (__debugfs_file_removed(), fs/debugfs/inode.c). Once it returns,
   no debugfs accessor can reach the FIB data, so the rhashtables and
   nsim_fib_data can be destroyed safely. This also covers the bool knobs
   in the same directory, which store pointers into the same
   nsim_fib_data, and the final kfree(data).

 - In nsim_fib_create(), create the debugfs files after the rhashtables
   and notifiers are set up. This closes the same race on the
   error-unwind path, where a concurrent writer could otherwise observe a
   half-constructed instance or a table that the unwind has already
   freed. (With only the destroy-side change, a writer racing the create
   window instead dereferences an uninitialized data->nexthop_ht.)

This is reproducible by racing, in a loop, writes to
/sys/kernel/debug/netdevsim/netdevsimN/fib/nexthop_bucket_activity
against a teardown of the same netdevsim instance -- a devlink reload
("devlink dev reload netdevsim/netdevsimN"), destroying the network
namespace it lives in, or "echo N > /sys/bus/netdevsim/del_device". It
was found with syzkaller; a syzkaller reproducer is available. A
standalone C reproducer does not trigger it reliably because the race
needs the netns-teardown/reload path.

Cc:  # netdevsim is a test harness, it's never loaded on production systems
Signed-off-by: Zijing Yin 
Reviewed-by: Ido Schimmel 
Link: https://patch.msgid.link/20260529135718.1804031-1-yzjaurora@gmail.com
Signed-off-by: Jakub Kicinski

devlink: pass param values by pointer

2026-05-25T21:03:06+00:00

union devlink_param_value grows substantially once U64 array
parameters are added to devlink (from 32 bytes to over 264 bytes).
devlink_nl_param_value_fill_one() and devlink_nl_param_value_put()
copy the union by value in several places. Passing two instances as
value arguments alone consumes over 528 bytes of stack; combined with
deeper call chains the parameter stack can approach 800 bytes and trip
CONFIG_FRAME_WARN more easily.

Switch internal helpers and exported driver APIs to pass pointers to
union devlink_param_value rather than passing the union by value.

Reviewed-by: Petr Machata  # for mlxsw
Acked-by: Przemek Kitszel 
Reviewed-by: Arthur Kiyanovski  #for ena
Signed-off-by: Ratheesh Kannoth 
Link: https://patch.msgid.link/20260521095303.2395584-4-rkannoth@marvell.com
Signed-off-by: Jakub Kicinski

netdevsim: psp: reset spi on key rotation and check for exhaustion on alloc

2026-05-18T23:27:18+00:00

The PSP spec states that the lower 31b of the SPI need to be
non-zero. Though not in the spec, I think it is reasonable to reset
the lower 31b of the spi space after a key rotation, and to also
decline to generate session keys when the lower 31b saturate.

Signed-off-by: Daniel Zahka 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20260515-spi-handle-v1-1-debf8cb467cb@gmail.com
Signed-off-by: Jakub Kicinski

netdevsim: psp: rcu protect psp_dev reference

2026-05-07T00:39:20+00:00

There are two issues with the way psp_dev is used in nsim_do_psp():

1. There is no check for IS_ERR() on the peers psp_dev, before
   dereferencing.
2. The refcount on this psp_dev can be dropped by
   nsim_psp_rereg_write()

To fix this, we can make netdevsim's reference to its psp_dev an rcu
reference, and then nsim_do_psp() can read the fields it needs from an
rcu critical section.

Fixes: f857478d6206 ("netdevsim: a basic test PSP implementation")
Signed-off-by: Daniel Zahka 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20260505-psd-rcu-v1-3-a8f69ec1ab96@gmail.com
Signed-off-by: Jakub Kicinski

netdevsim: psp: serialize calls to nsim_psp_uninit()

2026-05-07T00:39:20+00:00

The debugfs write handler, nsim_psp_rereg_write(), can race against
nsim_destroy() and against itself, causing nsim_psp_uninit() to run
more than once concurrently. Two complementary changes serialize all
callers:

1. Delete the psp_rereg debugfs file from nsim_psp_uninit() before
   doing the actual teardown. debugfs_remove() drains any in-flight
   writers and prevents new ones from starting.

2. Add a mutex around the body of nsim_psp_rereg_write() so that two
   concurrent userspace writers cannot both enter the teardown path
   at once.

The teardown work itself is moved into a new __nsim_psp_uninit() that
the rereg handler calls under the mutex, while the public
nsim_psp_uninit() wraps it with the debugfs_remove()/mutex_destroy()
pair so nsim_destroy() doesn't have to know about the psp internals.

Fixes: f857478d6206 ("netdevsim: a basic test PSP implementation")
Signed-off-by: Daniel Zahka 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20260505-psd-rcu-v1-2-a8f69ec1ab96@gmail.com
Signed-off-by: Jakub Kicinski