Currently, the net_device is allocated in ncm_alloc_inst() and freed in
ncm_free_inst(). This ties the network interface's lifetime to the
configuration instance rather than the USB connection (bind/unbind).
This decoupling causes issues when the USB gadget is disconnected where
the underlying gadget device is removed. The net_device can outlive its
parent, leading to dangling sysfs links and NULL pointer dereferences
when accessing the freed gadget device.
Problem 1: NULL pointer dereference on disconnect
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000000
Call trace:
__pi_strlen+0x14/0x150
rtnl_fill_ifinfo+0x6b4/0x708
rtmsg_ifinfo_build_skb+0xd8/0x13c
rtmsg_ifinfo+0x50/0xa0
__dev_notify_flags+0x4c/0x1f0
dev_change_flags+0x54/0x70
do_setlink+0x390/0xebc
rtnl_newlink+0x7d0/0xac8
rtnetlink_rcv_msg+0x27c/0x410
netlink_rcv_skb+0x134/0x150
rtnetlink_rcv+0x18/0x28
netlink_unicast+0x254/0x3f0
netlink_sendmsg+0x2e0/0x3d4
Problem 2: Dangling sysfs symlinks
console:/ # ls -l /sys/class/net/ncm0
lrwxrwxrwx ... /sys/class/net/ncm0 ->
/sys/devices/platform/.../gadget.0/net/ncm0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/ncm0
ls: .../gadget.0/net/ncm0: No such file or directory
Move the net_device allocation to ncm_bind() and deallocation to
ncm_unbind(). This ensures the network interface exists only when the
gadget function is actually bound to a configuration.
To support pre-bind configuration (e.g., setting interface name or MAC
address via configfs), cache user-provided options in f_ncm_opts
using the gether_opts structure. Apply these cached settings to the
net_device upon creation in ncm_bind().
Preserve the use-after-free fix from commit 6334b8e455 ("usb: gadget:
f_ncm: Fix UAF ncm object at re-bind after usb ep transport error").
Check opts->net in ncm_set_alt() and ncm_disable() to ensure
gether_disconnect() runs only if a connection was established.
Fixes: 40d133d7f5 ("usb: gadget: f_ncm: convert to new function interface with backward compatibility")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20251230-ncm-refactor-v1-3-793e347bc7a7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The max segment size is currently limited to the ethernet frame length of
the kernel which happens to be 1514 at this point in time. However the NCM
specification limits it to 64K for sixtenn bit NTB's. For peer to peer
connections, increasing the segment size gives better throughput.
Add support to configure this value before configfs symlink is created.
Also since the NTB Out/In buffer sizes are fixed at 16384 bytes, limit the
segment size to an upper cap of 8000 to allow at least a minimum of 2 MTU
sized datagrams to be aggregated.
Set the default MTU size for the ncm interface during function bind before
network interface is registered allowing MTU to be set in parity with
wMaxSegmentSize.
Update gadget documentation describing the new configfs property.
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Link: https://lore.kernel.org/r/20231221153216.18657-1-quic_kriskura@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch corrects the SPDX License Identifier style in
header files related to USB peripheral controller drivers.
For C header files Documentation/process/license-rules.rst
mandates C-like comments (opposed to C source files where
C++ style should be used).
Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
To be able to use the default USB class drivers available in Microsoft
Windows, we need to add OS descriptors to the exported USB gadget to
tell the OS that we are compatible with the built-in drivers.
Copy the OS descriptor support from f_rndis into f_ncm. As a result,
using the WINNCM compatible ID, the UsbNcm driver is loaded on
enumeration without the need for a custom driver or inf file.
Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
My @samusung.com address is going to cease existing soon, so change it to
an address which can actually be used to contact me.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.
Update the drivers/usb/ and include/linux/usb* files with the correct
SPDX license identifier based on the license text in the file itself.
The SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.
This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The drivers/usb/gadget directory contains many files.
Files which are related can be distributed into separate directories.
This patch moves the USB functions implementations into a separate directory.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
