linux.git/net/core/netdev-genl.c, branch v6.15 Linux kernel source tree net: devmem: fix kernel panic when netlink socket close after module unload 2025-05-15T15:05:32+00:00 Taehee Yoo ap420073@gmail.com 2025-05-14T15:40:28+00:00 0afc44d8cdf6029cce0a92873f0de5ac9416cec8 Kernel panic occurs when a devmem TCP socket is closed after NIC module is unloaded. This is Devmem TCP unregistration scenarios. number is an order. (a)netlink socket close (b)pp destroy (c)uninstall result 1 2 3 OK 1 3 2 (d)Impossible 2 1 3 OK 3 1 2 (e)Kernel panic 2 3 1 (d)Impossible 3 2 1 (d)Impossible (a) netdev_nl_sock_priv_destroy() is called when devmem TCP socket is closed. (b) page_pool_destroy() is called when the interface is down. (c) mp_ops->uninstall() is called when an interface is unregistered. (d) There is no scenario in mp_ops->uninstall() is called before page_pool_destroy(). Because unregister_netdevice_many_notify() closes interfaces first and then calls mp_ops->uninstall(). (e) netdev_nl_sock_priv_destroy() accesses struct net_device to acquire netdev_lock(). But if the interface module has already been removed, net_device pointer is invalid, so it causes kernel panic. In summary, there are only 3 possible scenarios. A. sk close -> pp destroy -> uninstall. B. pp destroy -> sk close -> uninstall. C. pp destroy -> uninstall -> sk close. Case C is a kernel panic scenario. In order to fix this problem, It makes mp_dmabuf_devmem_uninstall() set binding->dev to NULL. It indicates an bound net_device was unregistered. It makes netdev_nl_sock_priv_destroy() do not acquire netdev_lock() if binding->dev is NULL. A new binding->lock is added to protect a dev of a binding. So, lock ordering is like below. priv->lock netdev_lock(dev) binding->lock Tests: Scenario A: ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \ -v 7 -t 1 -q 1 & pid=$! sleep 10 kill $pid ip link set $interface down modprobe -rv $module Scenario B: ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \ -v 7 -t 1 -q 1 & pid=$! sleep 10 ip link set $interface down kill $pid modprobe -rv $module Scenario C: ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \ -v 7 -t 1 -q 1 & pid=$! sleep 10 modprobe -rv $module sleep 5 kill $pid Splat looks like: Oops: general protection fault, probably for non-canonical address 0xdffffc001fffa9f7: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI KASAN: probably user-memory-access in range [0x00000000fffd4fb8-0x00000000fffd4fbf] CPU: 0 UID: 0 PID: 2041 Comm: ncdevmem Tainted: G B W 6.15.0-rc1+ #2 PREEMPT(undef) 0947ec89efa0fd68838b78e36aa1617e97ff5d7f Tainted: [B]=BAD_PAGE, [W]=WARN RIP: 0010:__mutex_lock (./include/linux/sched.h:2244 kernel/locking/mutex.c:400 kernel/locking/mutex.c:443 kernel/locking/mutex.c:605 kernel/locking/mutex.c:746) Code: ea 03 80 3c 02 00 0f 85 4f 13 00 00 49 8b 1e 48 83 e3 f8 74 6a 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 34 48 89 fa 48 c1 ea 03 <0f> b6 f RSP: 0018:ffff88826f7ef730 EFLAGS: 00010203 RAX: dffffc0000000000 RBX: 00000000fffd4f88 RCX: ffffffffaa9bc811 RDX: 000000001fffa9f7 RSI: 0000000000000008 RDI: 00000000fffd4fbc RBP: ffff88826f7ef8b0 R08: 0000000000000000 R09: ffffed103e6aa1a4 R10: 0000000000000007 R11: ffff88826f7ef442 R12: fffffbfff669f65e R13: ffff88812a830040 R14: ffff8881f3550d20 R15: 00000000fffd4f88 FS: 0000000000000000(0000) GS:ffff888866c05000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000563bed0cb288 CR3: 00000001a7c98000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <TASK> ... netdev_nl_sock_priv_destroy (net/core/netdev-genl.c:953 (discriminator 3)) genl_release (net/netlink/genetlink.c:653 net/netlink/genetlink.c:694 net/netlink/genetlink.c:705) ... netlink_release (net/netlink/af_netlink.c:737) ... __sock_release (net/socket.c:647) sock_close (net/socket.c:1393) Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://patch.msgid.link/20250514154028.1062909-1-ap420073@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Kernel panic occurs when a devmem TCP socket is closed after NIC module
is unloaded.

This is Devmem TCP unregistration scenarios. number is an order.
(a)netlink socket close    (b)pp destroy    (c)uninstall    result
1                          2                3               OK
1                          3                2               (d)Impossible
2                          1                3               OK
3                          1                2               (e)Kernel panic
2                          3                1               (d)Impossible
3                          2                1               (d)Impossible

(a) netdev_nl_sock_priv_destroy() is called when devmem TCP socket is
    closed.
(b) page_pool_destroy() is called when the interface is down.
(c) mp_ops->uninstall() is called when an interface is unregistered.
(d) There is no scenario in mp_ops->uninstall() is called before
    page_pool_destroy().
    Because unregister_netdevice_many_notify() closes interfaces first
    and then calls mp_ops->uninstall().
(e) netdev_nl_sock_priv_destroy() accesses struct net_device to acquire
    netdev_lock().
    But if the interface module has already been removed, net_device
    pointer is invalid, so it causes kernel panic.

In summary, there are only 3 possible scenarios.
 A. sk close -> pp destroy -> uninstall.
 B. pp destroy -> sk close -> uninstall.
 C. pp destroy -> uninstall -> sk close.

Case C is a kernel panic scenario.

In order to fix this problem, It makes mp_dmabuf_devmem_uninstall() set
binding->dev to NULL.
It indicates an bound net_device was unregistered.

It makes netdev_nl_sock_priv_destroy() do not acquire netdev_lock()
if binding->dev is NULL.

A new binding->lock is added to protect a dev of a binding.
So, lock ordering is like below.
 priv->lock
 netdev_lock(dev)
 binding->lock

Tests:
Scenario A:
    ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \
        -v 7 -t 1 -q 1 &
    pid=$!
    sleep 10
    kill $pid
    ip link set $interface down
    modprobe -rv $module

Scenario B:
    ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \
        -v 7 -t 1 -q 1 &
    pid=$!
    sleep 10
    ip link set $interface down
    kill $pid
    modprobe -rv $module

Scenario C:
    ./ncdevmem -s 192.168.1.4 -c 192.168.1.2 -f $interface -l -p 8000 \
        -v 7 -t 1 -q 1 &
    pid=$!
    sleep 10
    modprobe -rv $module
    sleep 5
    kill $pid

Splat looks like:
Oops: general protection fault, probably for non-canonical address 0xdffffc001fffa9f7: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
KASAN: probably user-memory-access in range [0x00000000fffd4fb8-0x00000000fffd4fbf]
CPU: 0 UID: 0 PID: 2041 Comm: ncdevmem Tainted: G    B   W           6.15.0-rc1+ #2 PREEMPT(undef)  0947ec89efa0fd68838b78e36aa1617e97ff5d7f
Tainted: [B]=BAD_PAGE, [W]=WARN
RIP: 0010:__mutex_lock (./include/linux/sched.h:2244 kernel/locking/mutex.c:400 kernel/locking/mutex.c:443 kernel/locking/mutex.c:605 kernel/locking/mutex.c:746)
Code: ea 03 80 3c 02 00 0f 85 4f 13 00 00 49 8b 1e 48 83 e3 f8 74 6a 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 34 48 89 fa 48 c1 ea 03 <0f> b6 f
RSP: 0018:ffff88826f7ef730 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 00000000fffd4f88 RCX: ffffffffaa9bc811
RDX: 000000001fffa9f7 RSI: 0000000000000008 RDI: 00000000fffd4fbc
RBP: ffff88826f7ef8b0 R08: 0000000000000000 R09: ffffed103e6aa1a4
R10: 0000000000000007 R11: ffff88826f7ef442 R12: fffffbfff669f65e
R13: ffff88812a830040 R14: ffff8881f3550d20 R15: 00000000fffd4f88
FS:  0000000000000000(0000) GS:ffff888866c05000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563bed0cb288 CR3: 00000001a7c98000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
<TASK>
 ...
 netdev_nl_sock_priv_destroy (net/core/netdev-genl.c:953 (discriminator 3))
 genl_release (net/netlink/genetlink.c:653 net/netlink/genetlink.c:694 net/netlink/genetlink.c:705)
 ...
 netlink_release (net/netlink/af_netlink.c:737)
 ...
 __sock_release (net/socket.c:647)
 sock_close (net/socket.c:1393)

Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250514154028.1062909-1-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: export a helper for adding up queue stats 2025-05-08T09:56:12+00:00 Jakub Kicinski kuba@kernel.org 2025-05-07T00:32:20+00:00 23fa6a23d97182d36ca3c71e43c804fa91e46a03 Older drivers and drivers with lower queue counts often have a static array of queues, rather than allocating structs for each queue on demand. Add a helper for adding up qstats from a queue range. Expectation is that driver will pass a queue range [netdev->real_num_*x_queues, MAX). It was tempting to always use num_*x_queues as the end, but virtio seems to clamp its queue count after allocating the netdev. And this way we can trivaly reuse the helper for [0, real_..). Signed-off-by: Jakub Kicinski <kuba@kernel.org> Link: https://patch.msgid.link/20250507003221.823267-2-kuba@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
Older drivers and drivers with lower queue counts often have a static
array of queues, rather than allocating structs for each queue on demand.
Add a helper for adding up qstats from a queue range. Expectation is
that driver will pass a queue range [netdev->real_num_*x_queues, MAX).
It was tempting to always use num_*x_queues as the end, but virtio
seems to clamp its queue count after allocating the netdev. And this
way we can trivaly reuse the helper for [0, real_..).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250507003221.823267-2-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net: fix the missing unlock for detached devices 2025-04-22T00:10:49+00:00 Jakub Kicinski kuba@kernel.org 2025-04-18T01:53:17+00:00 d3153c3b42707d26c81083b426f2ef0951bce545 The combined condition was left as is when we converted from __dev_get_by_index() to netdev_get_by_index_lock(). There was no need to undo anything with the former, for the latter we need an unlock. Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations") Reviewed-by: Mina Almasry <almasrymina@google.com> Link: https://patch.msgid.link/20250418015317.1954107-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
The combined condition was left as is when we converted
from __dev_get_by_index() to netdev_get_by_index_lock().
There was no need to undo anything with the former, for
the latter we need an unlock.

Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations")
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250418015317.1954107-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: move mp dev config validation to __net_mp_open_rxq() 2025-04-04T14:35:38+00:00 Jakub Kicinski kuba@kernel.org 2025-04-03T01:34:04+00:00 ec304b70d46bd2ed66541c5b57b63276529e05b1 devmem code performs a number of safety checks to avoid having to reimplement all of them in the drivers. Move those to __net_mp_open_rxq() and reuse that function for binding to make sure that io_uring ZC also benefits from them. While at it rename the queue ID variable to rxq_idx in __net_mp_open_rxq(), we touch most of the relevant lines. The XArray insertion is reordered after the netdev_rx_queue_restart() call, otherwise we'd need to duplicate the queue index check or risk inserting an invalid pointer. The XArray allocation failures should be extremely rare. Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Fixes: 6e18ed929d3b ("net: add helpers for setting a memory provider on an rx queue") Link: https://patch.msgid.link/20250403013405.2827250-2-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
devmem code performs a number of safety checks to avoid having
to reimplement all of them in the drivers. Move those to
__net_mp_open_rxq() and reuse that function for binding to make
sure that io_uring ZC also benefits from them.

While at it rename the queue ID variable to rxq_idx in
__net_mp_open_rxq(), we touch most of the relevant lines.

The XArray insertion is reordered after the netdev_rx_queue_restart()
call, otherwise we'd need to duplicate the queue index check
or risk inserting an invalid pointer. The XArray allocation
failures should be extremely rare.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Fixes: 6e18ed929d3b ("net: add helpers for setting a memory provider on an rx queue")
Link: https://patch.msgid.link/20250403013405.2827250-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: fix use-after-free in the netdev_nl_sock_priv_destroy() 2025-03-31T23:44:49+00:00 Taehee Yoo ap420073@gmail.com 2025-03-28T06:22:37+00:00 42f342387841891bbbd15e25d33eb510a0cf7a9a In the netdev_nl_sock_priv_destroy(), an instance lock is acquired before calling net_devmem_unbind_dmabuf(), then releasing an instance lock(netdev_unlock(binding->dev)). However, a binding is freed in the net_devmem_unbind_dmabuf(). So using a binding after net_devmem_unbind_dmabuf() occurs UAF. To fix this UAF, it needs to use temporary variable. Fixes: ba6f418fbf64 ("net: bubble up taking netdev instance lock to callers of net_devmem_unbind_dmabuf()") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250328062237.3746875-1-ap420073@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
In the netdev_nl_sock_priv_destroy(), an instance lock is acquired
before calling net_devmem_unbind_dmabuf(), then releasing an instance
lock(netdev_unlock(binding->dev)).
However, a binding is freed in the net_devmem_unbind_dmabuf().
So using a binding after net_devmem_unbind_dmabuf() occurs UAF.
To fix this UAF, it needs to use temporary variable.

Fixes: ba6f418fbf64 ("net: bubble up taking netdev instance lock to callers of net_devmem_unbind_dmabuf()")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250328062237.3746875-1-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: designate queue counts as "double ops protected" by instance lock 2025-03-25T17:06:49+00:00 Jakub Kicinski kuba@kernel.org 2025-03-24T22:45:31+00:00 0a65dcf6249b75c841b4218426b0d246a805c7e0 Drivers which opt into instance lock protection of ops should only call set_real_num_*_queues() under the instance lock. This means that queue counts are double protected (writes are under both rtnl_lock and instance lock, readers under either). Some readers may still be under the rtnl_lock, however, so for now we need double protection of writers. OTOH queue API paths are only under the protection of the instance lock, so we need to validate that the instance is actually locking ops, otherwise the input checks we do against queue count are racy. Acked-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://patch.msgid.link/20250324224537.248800-6-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Drivers which opt into instance lock protection of ops should
only call set_real_num_*_queues() under the instance lock.
This means that queue counts are double protected (writes
are under both rtnl_lock and instance lock, readers under
either).

Some readers may still be under the rtnl_lock, however, so for
now we need double protection of writers.

OTOH queue API paths are only under the protection of the instance
lock, so we need to validate that the instance is actually locking
ops, otherwise the input checks we do against queue count are racy.

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250324224537.248800-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: bubble up taking netdev instance lock to callers of net_devmem_unbind_dmabuf() 2025-03-25T17:04:49+00:00 Jakub Kicinski kuba@kernel.org 2025-03-24T22:45:27+00:00 ba6f418fbf64bb8c0e98dc1b548c151beeedd16c A recent commit added taking the netdev instance lock in netdev_nl_bind_rx_doit(), but didn't remove it in net_devmem_unbind_dmabuf() which it calls from an error path. Always expect the callers of net_devmem_unbind_dmabuf() to hold the lock. This is consistent with net_devmem_bind_dmabuf(). (Not so) coincidentally this also protects mp_param with the instance lock, which the rest of this series needs. Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations") Reviewed-by: Mina Almasry <almasrymina@google.com> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://patch.msgid.link/20250324224537.248800-2-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
A recent commit added taking the netdev instance lock
in netdev_nl_bind_rx_doit(), but didn't remove it in
net_devmem_unbind_dmabuf() which it calls from an error path.
Always expect the callers of net_devmem_unbind_dmabuf() to
hold the lock. This is consistent with net_devmem_bind_dmabuf().

(Not so) coincidentally this also protects mp_param with the instance
lock, which the rest of this series needs.

Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations")
Reviewed-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250324224537.248800-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: drop rtnl_lock for queue_mgmt operations 2025-03-12T20:32:35+00:00 Stanislav Fomichev sdf@fomichev.me 2025-03-11T14:40:26+00:00 1d22d3060b9b1f33da617045480c59c4c0511196 All drivers that use queue API are already converted to use netdev instance lock. Move netdev instance lock management to the netlink layer and drop rtnl_lock. Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Mina Almasry. <almasrymina@google.com> Link: https://patch.msgid.link/20250311144026.4154277-4-sdf@fomichev.me Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
All drivers that use queue API are already converted to use
netdev instance lock. Move netdev instance lock management to
the netlink layer and drop rtnl_lock.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Mina Almasry. <almasrymina@google.com>
Link: https://patch.msgid.link/20250311144026.4154277-4-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: add granular lock for the netdev netlink socket 2025-03-12T20:32:35+00:00 Stanislav Fomichev sdf@fomichev.me 2025-03-11T14:40:25+00:00 10eef096be25f3811ada2b43b108d1b8d8170001 As we move away from rtnl_lock for queue ops, introduce per-netdev_nl_sock lock. Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Mina Almasry <almasrymina@google.com> Link: https://patch.msgid.link/20250311144026.4154277-3-sdf@fomichev.me Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
As we move away from rtnl_lock for queue ops, introduce
per-netdev_nl_sock lock.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250311144026.4154277-3-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: create netdev_nl_sock to wrap bindings list 2025-03-12T20:32:35+00:00 Stanislav Fomichev sdf@fomichev.me 2025-03-11T14:40:24+00:00 b6b67141d6f1f736b17aca87e5ecb43b7c3a8205 No functional changes. Next patches will add more granular locking to netdev_nl_sock. Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Mina Almasry <almasrymina@google.com> Link: https://patch.msgid.link/20250311144026.4154277-2-sdf@fomichev.me Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
No functional changes. Next patches will add more granular locking
to netdev_nl_sock.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250311144026.4154277-2-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>