linux-stable.git/drivers/usb, branch linux-5.10.y

usb: gadget: uvc: fix NULL pointer dereference during unbind race

2026-04-18T08:31:16+00:00

[ Upstream commit eba2936bbe6b752a31725a9eb5c674ecbf21ee7d ]

Commit b81ac4395bbe ("usb: gadget: uvc: allow for application to cleanly
shutdown") introduced two stages of synchronization waits totaling 1500ms
in uvc_function_unbind() to prevent several types of kernel panics.
However, this timing-based approach is insufficient during power
management (PM) transitions.

When the PM subsystem starts freezing user space processes, the
wait_event_interruptible_timeout() is aborted early, which allows the
unbind thread to proceed and nullify the gadget pointer
(cdev->gadget = NULL):

[  814.123447][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind()
[  814.178583][ T3173] PM: suspend entry (deep)
[  814.192487][ T3173] Freezing user space processes
[  814.197668][  T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release

When the PM subsystem resumes or aborts the suspend and tasks are
restarted, the V4L2 release path is executed and attempts to access the
already nullified gadget pointer, triggering a kernel panic:

[  814.292597][    C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake
[  814.386727][ T3173] Restarting tasks ...
[  814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030
[  814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4
[  814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94
[  814.404078][ T4558] Call trace:
[  814.404080][ T4558]  usb_gadget_deactivate+0x14/0xf4
[  814.404083][ T4558]  usb_function_deactivate+0x54/0x94
[  814.404087][ T4558]  uvc_function_disconnect+0x1c/0x5c
[  814.404092][ T4558]  uvc_v4l2_release+0x44/0xac
[  814.404095][ T4558]  v4l2_release+0xcc/0x130

Address the race condition and NULL pointer dereference by:

1. State Synchronization (flag + mutex)
Introduce a 'func_unbound' flag in struct uvc_device. This allows
uvc_function_disconnect() to safely skip accessing the nullified
cdev->gadget pointer. As suggested by Alan Stern, this flag is protected
by a new mutex (uvc->lock) to ensure proper memory ordering and prevent
instruction reordering or speculative loads. This mutex is also used to
protect 'func_connected' for consistent state management.

2. Explicit Synchronization (completion)
Use a completion to synchronize uvc_function_unbind() with the
uvc_vdev_release() callback. This prevents Use-After-Free (UAF) by
ensuring struct uvc_device is freed after all video device resources
are released.

Fixes: b81ac4395bbe ("usb: gadget: uvc: allow for application to cleanly shutdown")
Cc: stable 
Suggested-by: Alan Stern 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: Jimmy Hu 
Link: https://patch.msgid.link/20260320065427.1374555-1-hhhuuu@google.com
Signed-off-by: Greg Kroah-Hartman 
[ replaced guard()/scoped_guard() macros ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop

2026-04-18T08:31:16+00:00

[ Upstream commit e1eabb072c75681f78312c484ccfffb7430f206e ]

A race condition between gether_disconnect() and eth_stop() leads to a
NULL pointer dereference. Specifically, if eth_stop() is triggered
concurrently while gether_disconnect() is tearing down the endpoints,
eth_stop() attempts to access the cleared endpoint descriptor, causing
the following NPE:

  Unable to handle kernel NULL pointer dereference
  Call trace:
   __dwc3_gadget_ep_enable+0x60/0x788
   dwc3_gadget_ep_enable+0x70/0xe4
   usb_ep_enable+0x60/0x15c
   eth_stop+0xb8/0x108

Because eth_stop() crashes while holding the dev->lock, the thread
running gether_disconnect() fails to acquire the same lock and spins
forever, resulting in a hardlockup:

  Core - Debugging Information for Hardlockup core(7)
  Call trace:
   queued_spin_lock_slowpath+0x94/0x488
   _raw_spin_lock+0x64/0x6c
   gether_disconnect+0x19c/0x1e8
   ncm_set_alt+0x68/0x1a0
   composite_setup+0x6a0/0xc50

The root cause is that the clearing of dev->port_usb in
gether_disconnect() is delayed until the end of the function.

Move the clearing of dev->port_usb to the very beginning of
gether_disconnect() while holding dev->lock. This cuts off the link
immediately, ensuring eth_stop() will see dev->port_usb as NULL and
safely bail out.

Fixes: 2b3d942c4878 ("usb ethernet gadget: split out network core")
Cc: stable 
Signed-off-by: Kuen-Han Tsai 
Link: https://patch.msgid.link/20260311-gether-disconnect-npe-v1-1-454966adf7c7@google.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_hid: move list and spinlock inits from bind to alloc

2026-04-18T08:31:16+00:00

[ Upstream commit 4e0a88254ad59f6c53a34bf5fa241884ec09e8b2 ]

There was an issue when you did the following:
- setup and bind an hid gadget
- open /dev/hidg0
- use the resulting fd in EPOLL_CTL_ADD
- unbind the UDC
- bind the UDC
- use the fd in EPOLL_CTL_DEL

When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported
within remove_wait_queue (via ep_remove_wait_queue). After some
debugging I found out that the queues, which f_hid registers via
poll_wait were the problem. These were initialized using
init_waitqueue_head inside hidg_bind. So effectively, the bind function
re-initialized the queues while there were still items in them.

The solution is to move the initialization from hidg_bind to hidg_alloc
to extend their lifetimes to the lifetime of the function instance.

Additionally, I found many other possibly problematic init calls in the
bind function, which I moved as well.

Signed-off-by: Michael Zimmermann 
Cc: stable 
Link: https://patch.msgid.link/20260331184844.2388761-1-sigmaepsilon92@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_uac1_legacy: validate control request size

2026-04-18T08:31:13+00:00

commit 6e0e34d85cd46ceb37d16054e97a373a32770f6c upstream.

f_audio_complete() copies req->length bytes into a 4-byte stack
variable:

  u32 data = 0;
  memcpy(&data, req->buf, req->length);

req->length is derived from the host-controlled USB request path,
which can lead to a stack out-of-bounds write.

Validate req->actual against the expected payload size for the
supported control selectors and decode only the expected amount
of data.

This avoids copying a host-influenced length into a fixed-size
stack object.

Signed-off-by: Taegu Ha 
Cc: stable 
Link: https://patch.msgid.link/20260401191311.3604898-1-hataegu0826@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_rndis: Protect RNDIS options with mutex

2026-04-18T08:31:13+00:00

commit 8d8c68b1fc06ece60cf43e1306ff0f4ac121547e upstream.

The class/subclass/protocol options are suspectible to race conditions
as they can be accessed concurrently through configfs.

Use existing mutex to protect these options. This issue was identified
during code inspection.

Fixes: 73517cf49bd4 ("usb: gadget: add RNDIS configfs options for class/subclass/protocol")
Cc: stable@vger.kernel.org
Signed-off-by: Kuen-Han Tsai 
Link: https://patch.msgid.link/20260320-usb-net-lifecycle-v1-2-4886b578161b@google.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_subset: Fix unbalanced refcnt in geth_free

2026-04-18T08:31:13+00:00

commit caa27923aacd8a5869207842f2ab1657c6c0c7bc upstream.

geth_alloc() increments the reference count, but geth_free() fails to
decrement it. This prevents the configuration of attributes via configfs
after unlinking the function.

Decrement the reference count in geth_free() to ensure proper cleanup.

Fixes: 02832e56f88a ("usb: gadget: f_subset: add configfs support")
Cc: stable@vger.kernel.org
Signed-off-by: Kuen-Han Tsai 
Link: https://patch.msgid.link/20260320-usb-net-lifecycle-v1-1-4886b578161b@google.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: dummy_hcd: fix premature URB completion when ZLP follows partial transfer

2026-04-18T08:31:13+00:00

commit f50200dd44125e445a6164e88c217472fa79cdbc upstream.

When a gadget request is only partially transferred in transfer()
because the per-frame bandwidth budget is exhausted, the loop advances
to the next queued request. If that next request is a zero-length
packet (ZLP), len evaluates to zero and the code takes the
unlikely(len == 0) path, which sets is_short = 1. This bypasses the
bandwidth guard ("limit < ep->ep.maxpacket && limit < len") that
lives in the else branch and would otherwise break out of the loop for
non-zero requests. The is_short path then completes the URB before all
data from the first request has been transferred.

Reproducer (bulk IN, high speed):

  Device side (FunctionFS with Linux AIO):
    1. Queue a 65024-byte write via io_submit (127 * 512, i.e. a
       multiple of the HS bulk max packet size).
    2. Immediately queue a zero-length write (ZLP) via io_submit.

  Host side:
    3. Submit a 65536-byte bulk IN URB.

  Expected: URB completes with actual_length = 65024.
  Actual:   URB completes with actual_length = 53248, losing 11776
            bytes that leak into subsequent URBs.

At high speed the per-frame budget is 53248 bytes (512 * 13 * 8).
The 65024-byte request exhausts this budget after 53248 bytes, leaving
the request incomplete (req->req.actual < req->req.length). Neither
the request nor the URB is finished, and rescan is 0, so the loop
advances to the ZLP. For the ZLP, dev_len = 0, so len = min(12288, 0)
= 0, taking the unlikely(len == 0) path and setting is_short = 1.
The is_short handler then sets *status = 0, completing the URB with
only 53248 of the expected 65024 bytes.

Fix this by breaking out of the loop when the current request has
remaining data (req->req.actual < req->req.length). The request
resumes on the next timer tick, preserving correct data ordering.

Signed-off-by: Sebastian Urban 
Cc: stable 
Reviewed-by: Alan Stern 
Link: https://patch.msgid.link/20260315151045.1155850-1-surban@surban.net
Signed-off-by: Greg Kroah-Hartman

USB: dummy-hcd: Fix locking/synchronization error

2026-04-18T08:31:13+00:00

commit 616a63ff495df12863692ab3f9f7b84e3fa7a66d upstream.

Syzbot testing was able to provoke an addressing exception and crash
in the usb_gadget_udc_reset() routine in
drivers/usb/gadgets/udc/core.c, resulting from the fact that the
routine was called with a second ("driver") argument of NULL.  The bad
caller was set_link_state() in dummy_hcd.c, and the problem arose
because of a race between a USB reset and driver unbind.

These sorts of races were not supposed to be possible; commit
7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"),
along with a few followup commits, was written specifically to prevent
them.  As it turns out, there are (at least) two errors remaining in
the code.  Another patch will address the second error; this one is
concerned with the first.

The error responsible for the syzbot crash occurred because the
stop_activity() routine will sometimes drop and then re-acquire the
dum->lock spinlock.  A call to stop_activity() occurs in
set_link_state() when handling an emulated USB reset, after the test
of dum->ints_enabled and before the increment of dum->callback_usage.
This allowed another thread (doing a driver unbind) to sneak in and
grab the spinlock, and then clear dum->ints_enabled and dum->driver.
Normally this other thread would have to wait for dum->callback_usage
to go down to 0 before it would clear dum->driver, but in this case it
didn't have to wait since dum->callback_usage had not yet been
incremented.

The fix is to increment dum->callback_usage _before_ calling
stop_activity() instead of after.  Then the thread doing the unbind
will not clear dum->driver until after the call to
usb_gadget_udc_reset() safely returns and dum->callback_usage has been
decremented again.

Signed-off-by: Alan Stern 
Reported-by: syzbot+19bed92c97bee999e5db@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-usb/68fc7c9c.050a0220.346f24.023c.GAE@google.com/
Tested-by: syzbot+19bed92c97bee999e5db@syzkaller.appspotmail.com
Fixes: 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change")
Cc: stable 
Link: https://patch.msgid.link/46135f42-fdbe-46b5-aac0-6ca70492af15@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman

cdc-acm: new quirk for EPSON HMD

2026-04-18T08:31:12+00:00

commit f97e96c303d689708f7f713d8f3afcc31f1237e9 upstream.

This device has a union descriptor that is just garbage
and needs a custom descriptor.
In principle this could be done with a (conditionally
activated) heuristic. That would match more devices
without a need for defining a new quirk. However,
this always carries the risk that the heuristics
does the wrong thing and leads to more breakage.
Defining the quirk and telling it exactly what to do
is the safe and conservative approach.

Signed-off-by: Oliver Neukum 
Cc: stable 
Link: https://patch.msgid.link/20260317084139.1461008-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman

usb: ehci-brcm: fix sleep during atomic

2026-04-18T08:31:12+00:00

commit 679b771ea05ad0f8eeae83e14a91b8f4f39510c4 upstream.

echi_brcm_wait_for_sof() gets called after disabling interrupts
in ehci_brcm_hub_control(). Use the atomic version of poll_timeout
to fix the warning.

Fixes: 9df231511bd6 ("usb: ehci: Add new EHCI driver for Broadcom STB SoC's")
Cc: stable 
Signed-off-by: Justin Chen 
Reviewed-by: Florian Fainelli 
Link: https://patch.msgid.link/20260318185707.2588431-1-justin.chen@broadcom.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman