kernel/linux.git/drivers/usb/gadget/function/f_uvc.c, branch v6.19.12

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

2026-04-11T12:29:57+00:00

commit eba2936bbe6b752a31725a9eb5c674ecbf21ee7d upstream. 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 Signed-off-by: Jimmy Hu Link: https://patch.msgid.link/20260320065427.1374555-1-hhhuuu@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

usb: gadget: uvc: fix req_payload_size calculation

2026-01-14T15:03:17+00:00

Current req_payload_size calculation has 2 issue: (1) When the first time calculate req_payload_size for all the buffers, reqs_per_frame = 0 will be the divisor of DIV_ROUND_UP(). So the result is undefined. This happens because VIDIOC_STREAMON is always executed after VIDIOC_QBUF. So video->reqs_per_frame will be 0 until VIDIOC_STREAMON is run. (2) The buf->req_payload_size may be bigger than max_req_size. Take YUYV pixel format as example: If bInterval = 1, video->interval = 666666, high-speed: video->reqs_per_frame = 666666 / 1250 = 534 720p: buf->req_payload_size = 1843200 / 534 = 3452 1080p: buf->req_payload_size = 4147200 / 534 = 7766 Based on such req_payload_size, the controller can't run normally. To fix above issue, assign max_req_size to buf->req_payload_size when video->reqs_per_frame = 0. And limit buf->req_payload_size to video->req_size if it's large than video->req_size. Since max_req_size is used at many place, add it to struct uvc_video and set the value once endpoint is enabled. Fixes: 98ad03291560 ("usb: gadget: uvc: set req_length based on payload by nreqs instead of req_size") Cc: stable@vger.kernel.org Reviewed-by: Frank Li Signed-off-by: Xu Yang Link: https://patch.msgid.link/20260113-uvc-gadget-fix-patch-v2-1-62950ef5bcb5@nxp.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: uvc: rework to enqueue in pump worker from encoded queue

2024-10-17T06:42:22+00:00

We install an kthread with pfifo priority that is iterating over all prepared requests and keeps the isoc queue busy. This way it will be scheduled with the same priority as the interrupt handler. As the kthread is triggered with video_enable it will immediately queue some zero length requests into the hw if there is no buffer data available. It also watches the level of needed zero length requests in the hardware not to fall under the UVCG_REQ_MAX_ZERO_COUNT threshold. This way we can drop the function uvc_video_ep_queue_initial_requests entirely. By using the kthread to do the actual request handling the interrupt handler will not be running into the time consuming and eventually locking work of actually enqueueing the requests back into its own pipeline. This work can now even be scheduled on another cpu. Signed-off-by: Michael Grzeschik Link: https://lore.kernel.org/r/20240403-uvc_request_length_by_interval-v7-3-e224bb1035f0@pengutronix.de Signed-off-by: Greg Kroah-Hartman

usb: gadget: uvc: Remove extra semicolon from the macro

2024-10-16T08:17:49+00:00

Remove the extra semicolon after the do {} while (0) in UVC_COPY_DESCRIPTOR macro. Fix the following checkpatch.pl warning WARNING: do {} while (0) macros should not be semicolon terminated +#define UVC_COPY_DESCRIPTOR(mem, dst, desc) \ + do { \ + memcpy(mem, desc, (desc)->bLength); \ + *(dst)++ = mem; \ + mem += (desc)->bLength; \ + } while (0); Signed-off-by: Abhishek Tamboli Reviewed-by: Kieran Bingham Link: https://lore.kernel.org/r/20241013142511.9946-1-abhishektamboli9@gmail.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: add missing MODULE_DESCRIPTION() macros

2024-06-20T17:18:19+00:00

make allmodconfig && make W=1 C=1 reports: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/libcomposite.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_acm.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_ss_lb.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/u_serial.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_serial.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_obex.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/u_ether.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_ncm.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_ecm.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_phonet.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_eem.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_ecm_subset.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_rndis.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_mass_storage.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_fs.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_uac1.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_uac1_legacy.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_uac2.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_uvc.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_midi.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_midi2.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_hid.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_printer.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/function/usb_f_tcm.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/legacy/g_zero.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/legacy/g_midi.o WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/usb/gadget/legacy/g_dbgp.o Add the missing invocations of the MODULE_DESCRIPTION() macro. Signed-off-by: Jeff Johnson Link: https://lore.kernel.org/r/20240605-md-drivers-usb-gadget-v1-1-29847a46aad3@quicinc.com Signed-off-by: Greg Kroah-Hartman

Revert "usb: gadget: f_uvc: change endpoint allocation in uvc_function_bind()"

2024-01-04T15:01:45+00:00

This reverts commit 3c5b006f3ee800b4bd9ed37b3a8f271b8560126e. gadget_is_{super|dual}speed() API check UDC controller capitblity. It should pass down highest speed endpoint descriptor to UDC controller. So UDC controller driver can reserve enough resource at check_config(), especially mult and maxburst. So UDC driver (such as cdns3) can know need at least (mult + 1) * (maxburst + 1) * wMaxPacketSize internal memory for this uvc functions. Cc: Signed-off-by: Frank Li Link: https://lore.kernel.org/r/20231224153816.1664687-5-Frank.Li@nxp.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: webcam: Make g_webcam loadable again

2023-12-15T17:27:38+00:00

commit 588b9e85609b ("usb: gadget: uvc: add v4l2 enumeration api calls") has rendered the precomposed (aka legacy) webcam gadget unloadable. uvc_alloc() since then has depended on certain config groups being available in configfs tree related to the UVC function. However, legacy gadgets do not create anything in configfs, so uvc_alloc() must fail with -ENOENT no matter what. This patch mimics the required configfs hierarchy to satisfy the code which inspects formats and frames found in uvcg_streaming_header. This has been tested with guvcview on the host side, using vivid as a source of video stream on the device side and using the userspace program found at https://gitlab.freedesktop.org/camera/uvc-gadget.git. Signed-off-by: Andrzej Pietrasiewicz Fixes: 588b9e85609b ("usb: gadget: uvc: add v4l2 enumeration api calls") Link: https://lore.kernel.org/r/20231215131614.29132-1-andrzej.p@collabora.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: uvc: prevent use of disabled endpoint

2023-11-23T12:32:44+00:00

Currently the set_alt callback immediately disables the endpoint and queues the v4l2 streamoff event. However, as the streamoff event is processed asynchronously, it is possible that the video_pump thread attempts to queue requests to an already disabled endpoint. This change moves disabling usb endpoint to the end of streamoff event callback. As the endpoint's state can no longer be used, video_pump is now guarded by uvc->state as well. To be consistent with the actual streaming state, uvc->state is now toggled between CONNECTED and STREAMING from the v4l2 event callback only. Link: https://lore.kernel.org/20230615171558.GK741@pendragon.ideasonboard.com/ Link: https://lore.kernel.org/20230531085544.253363-1-dan.scally@ideasonboard.com/ Reviewed-by: Daniel Scally Reviewed-by: Michael Grzeschik Tested-by: Michael Grzeschik Signed-off-by: Avichal Rakesh Link: https://lore.kernel.org/r/20231109004104.3467968-1-arakesh@google.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: uvc: Add missing initialization of ssp config descriptor

2023-10-28T10:25:19+00:00

In case the uvc gadget is super speed plus, the corresponding config descriptor wasn't initialized. As a result, the host will not recognize the devices when using super speed plus connection. This patch initializes them to super speed descriptors. Reviewed-by: Laurent Pinchart Signed-off-by: Shuzhen Wang Link: https://lore.kernel.org/r/20231027183440.1994315-1-shuzhenwang@google.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: unconditionally allocate hs/ss descriptor in bind operation

2023-08-22T12:48:33+00:00

Take f_midi_bind() for example, when composite layer call it, it will allocate hs descriptor by calling gadget_is_dualspeed() API to check gadget max support speed capability, but most other gadget function didn't do like this. To follow other function drivers, it is safe to remove the check which mean support all possible link speed by default in function driver. Similar change apply to midi2 and uvc. Also in midi and midi2, as there is no descriptor difference between super speed and super speed plus, follow other gadget function drivers, do not allocate descriptor for super speed plus, composite layer will handle it properly. Signed-off-by: Linyu Yuan Link: https://lore.kernel.org/r/20230803091053.9714-5-quic_linyyuan@quicinc.com Signed-off-by: Greg Kroah-Hartman