From: Thadeu Lima de Souza Cascardo cascardo@igalia.com

Per UVC 1.1+ specification 3.7.2, units and terminals must have a non-zero unique ID.

``` Each Unit and Terminal within the video function is assigned a unique identification number, the Unit ID (UID) or Terminal ID (TID), contained in the bUnitID or bTerminalID field of the descriptor. The value 0x00 is reserved for undefined ID, ```

If we add a new entity with id 0 or a duplicated ID, it will be marked as UVC_INVALID_ENTITY_ID.

In a previous attempt commit 3dd075fe8ebb ("media: uvcvideo: Require entities to have a non-zero unique ID"), we ignored all the invalid units, this broke a lot of non-compatible cameras. Hopefully we are more lucky this time.

This also prevents some syzkaller reproducers from triggering warnings due to a chain of entities referring to themselves. In one particular case, an Output Unit is connected to an Input Unit, both with the same ID of 1. But when looking up for the source ID of the Output Unit, that same entity is found instead of the input entity, which leads to such warnings.

In another case, a backward chain was considered finished as the source ID was 0. Later on, that entity was found, but its pads were not valid.

Here is a sample stack trace for one of those cases.

[ 20.650953] usb 1-1: new high-speed USB device number 2 using dummy_hcd [ 20.830206] usb 1-1: Using ep0 maxpacket: 8 [ 20.833501] usb 1-1: config 0 descriptor?? [ 21.038518] usb 1-1: string descriptor 0 read error: -71 [ 21.038893] usb 1-1: Found UVC 0.00 device <unnamed> (2833:0201) [ 21.039299] uvcvideo 1-1:0.0: Entity type for entity Output 1 was not initialized! [ 21.041583] uvcvideo 1-1:0.0: Entity type for entity Input 1 was not initialized! [ 21.042218] ------------[ cut here ]------------ [ 21.042536] WARNING: CPU: 0 PID: 9 at drivers/media/mc/mc-entity.c:1147 media_create_pad_link+0x2c4/0x2e0 [ 21.043195] Modules linked in: [ 21.043535] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.11.0-rc7-00030-g3480e43aeccf #444 [ 21.044101] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 [ 21.044639] Workqueue: usb_hub_wq hub_event [ 21.045100] RIP: 0010:media_create_pad_link+0x2c4/0x2e0 [ 21.045508] Code: fe e8 20 01 00 00 b8 f4 ff ff ff 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 0f 0b eb e9 0f 0b eb 0a 0f 0b eb 06 <0f> 0b eb 02 0f 0b b8 ea ff ff ff eb d4 66 2e 0f 1f 84 00 00 00 00 [ 21.046801] RSP: 0018:ffffc9000004b318 EFLAGS: 00010246 [ 21.047227] RAX: ffff888004e5d458 RBX: 0000000000000000 RCX: ffffffff818fccf1 [ 21.047719] RDX: 000000000000007b RSI: 0000000000000000 RDI: ffff888004313290 [ 21.048241] RBP: ffff888004313290 R08: 0001ffffffffffff R09: 0000000000000000 [ 21.048701] R10: 0000000000000013 R11: 0001888004313290 R12: 0000000000000003 [ 21.049138] R13: ffff888004313080 R14: ffff888004313080 R15: 0000000000000000 [ 21.049648] FS: 0000000000000000(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000 [ 21.050271] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.050688] CR2: 0000592cc27635b0 CR3: 000000000431c000 CR4: 0000000000750ef0 [ 21.051136] PKRU: 55555554 [ 21.051331] Call Trace: [ 21.051480] <TASK> [ 21.051611] ? __warn+0xc4/0x210 [ 21.051861] ? media_create_pad_link+0x2c4/0x2e0 [ 21.052252] ? report_bug+0x11b/0x1a0 [ 21.052540] ? trace_hardirqs_on+0x31/0x40 [ 21.052901] ? handle_bug+0x3d/0x70 [ 21.053197] ? exc_invalid_op+0x1a/0x50 [ 21.053511] ? asm_exc_invalid_op+0x1a/0x20 [ 21.053924] ? media_create_pad_link+0x91/0x2e0 [ 21.054364] ? media_create_pad_link+0x2c4/0x2e0 [ 21.054834] ? media_create_pad_link+0x91/0x2e0 [ 21.055131] ? _raw_spin_unlock+0x1e/0x40 [ 21.055441] ? __v4l2_device_register_subdev+0x202/0x210 [ 21.055837] uvc_mc_register_entities+0x358/0x400 [ 21.056144] uvc_register_chains+0x1fd/0x290 [ 21.056413] uvc_probe+0x380e/0x3dc0 [ 21.056676] ? __lock_acquire+0x5aa/0x26e0 [ 21.056946] ? find_held_lock+0x33/0xa0 [ 21.057196] ? kernfs_activate+0x70/0x80 [ 21.057533] ? usb_match_dynamic_id+0x1b/0x70 [ 21.057811] ? find_held_lock+0x33/0xa0 [ 21.058047] ? usb_match_dynamic_id+0x55/0x70 [ 21.058330] ? lock_release+0x124/0x260 [ 21.058657] ? usb_match_one_id_intf+0xa2/0x100 [ 21.058997] usb_probe_interface+0x1ba/0x330 [ 21.059399] really_probe+0x1ba/0x4c0 [ 21.059662] __driver_probe_device+0xb2/0x180 [ 21.059944] driver_probe_device+0x5a/0x100 [ 21.060170] __device_attach_driver+0xe9/0x160 [ 21.060427] ? __pfx___device_attach_driver+0x10/0x10 [ 21.060872] bus_for_each_drv+0xa9/0x100 [ 21.061312] __device_attach+0xed/0x190 [ 21.061812] device_initial_probe+0xe/0x20 [ 21.062229] bus_probe_device+0x4d/0xd0 [ 21.062590] device_add+0x308/0x590 [ 21.062912] usb_set_configuration+0x7b6/0xaf0 [ 21.063403] usb_generic_driver_probe+0x36/0x80 [ 21.063714] usb_probe_device+0x7b/0x130 [ 21.063936] really_probe+0x1ba/0x4c0 [ 21.064111] __driver_probe_device+0xb2/0x180 [ 21.064577] driver_probe_device+0x5a/0x100 [ 21.065019] __device_attach_driver+0xe9/0x160 [ 21.065403] ? __pfx___device_attach_driver+0x10/0x10 [ 21.065820] bus_for_each_drv+0xa9/0x100 [ 21.066094] __device_attach+0xed/0x190 [ 21.066535] device_initial_probe+0xe/0x20 [ 21.066992] bus_probe_device+0x4d/0xd0 [ 21.067250] device_add+0x308/0x590 [ 21.067501] usb_new_device+0x347/0x610 [ 21.067817] hub_event+0x156b/0x1e30 [ 21.068060] ? process_scheduled_works+0x48b/0xaf0 [ 21.068337] process_scheduled_works+0x5a3/0xaf0 [ 21.068668] worker_thread+0x3cf/0x560 [ 21.068932] ? kthread+0x109/0x1b0 [ 21.069133] kthread+0x197/0x1b0 [ 21.069343] ? __pfx_worker_thread+0x10/0x10 [ 21.069598] ? __pfx_kthread+0x10/0x10 [ 21.069908] ret_from_fork+0x32/0x40 [ 21.070169] ? __pfx_kthread+0x10/0x10 [ 21.070424] ret_from_fork_asm+0x1a/0x30 [ 21.070737] </TASK>

Cc: stable@vger.kernel.org Reported-by: syzbot+0584f746fde3d52b4675@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0584f746fde3d52b4675 Reported-by: syzbot+dd320d114deb3f5bb79b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=dd320d114deb3f5bb79b Fixes: a3fbc2e6bb05 ("media: mc-entity.c: use WARN_ON, validate link pads") Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@igalia.com Co-developed-by: Ricardo Ribalda ribalda@chromium.org Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- This is a new attempt to land a Thadeu's patch, but being a bit more benevolent on the non-compliant cameras.

I have kept most of Thadeu's code, but instead of returning an error when trying to allocate an invalid entity, I replace its id with a special ID.

Thadeu can you validate this new version?

Tomasz can you also check this patch with your non compliant camera?

Thanks! --- drivers/media/usb/uvc/uvc_driver.c | 73 ++++++++++++++++++++++++-------------- drivers/media/usb/uvc/uvcvideo.h | 2 ++ 2 files changed, 48 insertions(+), 27 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index 775bede0d93d9b3e5391914aa395326d3de6a3b1..46923cd85f0b6790f01ae6b393571ca7660900f7 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -137,6 +137,9 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id) { struct uvc_entity *entity;

+ if (id == UVC_INVALID_ENTITY_ID) + return NULL; + list_for_each_entry(entity, &dev->entities, list) { if (entity->id == id) return entity; @@ -795,14 +798,27 @@ static const u8 uvc_media_transport_input_guid[16] = UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT; static const u8 uvc_processing_guid[16] = UVC_GUID_UVC_PROCESSING;

-static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id, - unsigned int num_pads, unsigned int extra_size) +static struct uvc_entity *uvc_alloc_new_entity(struct uvc_device *dev, u16 type, + u16 id, unsigned int num_pads, + unsigned int extra_size) { struct uvc_entity *entity; unsigned int num_inputs; unsigned int size; unsigned int i;

+ /* Per UVC 1.1+ spec 3.7.2, the ID should be non-zero. */ + if (id == 0) { + dev_err(&dev->intf->dev, "Found Unit with invalid ID 0.\n"); + id = UVC_INVALID_ENTITY_ID; + } + + /* Per UVC 1.1+ spec 3.7.2, the ID is unique. */ + if (uvc_entity_by_id(dev, id)) { + dev_err(&dev->intf->dev, "Found multiple Units with ID %u\n", id); + id = UVC_INVALID_ENTITY_ID; + } + extra_size = roundup(extra_size, sizeof(*entity->pads)); if (num_pads) num_inputs = type & UVC_TERM_OUTPUT ? num_pads : num_pads - 1; @@ -812,7 +828,7 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id, + num_inputs; entity = kzalloc(size, GFP_KERNEL); if (entity == NULL) - return NULL; + return ERR_PTR(-ENOMEM);

entity->id = id; entity->type = type; @@ -924,10 +940,10 @@ static int uvc_parse_vendor_control(struct uvc_device *dev, break; }

- unit = uvc_alloc_entity(UVC_VC_EXTENSION_UNIT, buffer[3], - p + 1, 2*n); - if (unit == NULL) - return -ENOMEM; + unit = uvc_alloc_new_entity(dev, UVC_VC_EXTENSION_UNIT, + buffer[3], p + 1, 2 * n); + if (IS_ERR(unit)) + return PTR_ERR(unit);

memcpy(unit->guid, &buffer[4], 16); unit->extension.bNumControls = buffer[20]; @@ -1036,10 +1052,10 @@ static int uvc_parse_standard_control(struct uvc_device *dev, return -EINVAL; }

- term = uvc_alloc_entity(type | UVC_TERM_INPUT, buffer[3], - 1, n + p); - if (term == NULL) - return -ENOMEM; + term = uvc_alloc_new_entity(dev, type | UVC_TERM_INPUT, + buffer[3], 1, n + p); + if (IS_ERR(term)) + return PTR_ERR(term);

if (UVC_ENTITY_TYPE(term) == UVC_ITT_CAMERA) { term->camera.bControlSize = n; @@ -1095,10 +1111,10 @@ static int uvc_parse_standard_control(struct uvc_device *dev, return 0; }

- term = uvc_alloc_entity(type | UVC_TERM_OUTPUT, buffer[3], - 1, 0); - if (term == NULL) - return -ENOMEM; + term = uvc_alloc_new_entity(dev, type | UVC_TERM_OUTPUT, + buffer[3], 1, 0); + if (IS_ERR(term)) + return PTR_ERR(term);

memcpy(term->baSourceID, &buffer[7], 1);

@@ -1117,9 +1133,10 @@ static int uvc_parse_standard_control(struct uvc_device *dev, return -EINVAL; }

- unit = uvc_alloc_entity(buffer[2], buffer[3], p + 1, 0); - if (unit == NULL) - return -ENOMEM; + unit = uvc_alloc_new_entity(dev, buffer[2], buffer[3], + p + 1, 0); + if (IS_ERR(unit)) + return PTR_ERR(unit);

memcpy(unit->baSourceID, &buffer[5], p);

@@ -1139,9 +1156,9 @@ static int uvc_parse_standard_control(struct uvc_device *dev, return -EINVAL; }

- unit = uvc_alloc_entity(buffer[2], buffer[3], 2, n); - if (unit == NULL) - return -ENOMEM; + unit = uvc_alloc_new_entity(dev, buffer[2], buffer[3], 2, n); + if (IS_ERR(unit)) + return PTR_ERR(unit);

memcpy(unit->baSourceID, &buffer[4], 1); unit->processing.wMaxMultiplier = @@ -1168,9 +1185,10 @@ static int uvc_parse_standard_control(struct uvc_device *dev, return -EINVAL; }

- unit = uvc_alloc_entity(buffer[2], buffer[3], p + 1, n); - if (unit == NULL) - return -ENOMEM; + unit = uvc_alloc_new_entity(dev, buffer[2], buffer[3], + p + 1, n); + if (IS_ERR(unit)) + return PTR_ERR(unit);

memcpy(unit->guid, &buffer[4], 16); unit->extension.bNumControls = buffer[20]; @@ -1315,9 +1333,10 @@ static int uvc_gpio_parse(struct uvc_device *dev) return dev_err_probe(&dev->intf->dev, irq, "No IRQ for privacy GPIO\n");

- unit = uvc_alloc_entity(UVC_EXT_GPIO_UNIT, UVC_EXT_GPIO_UNIT_ID, 0, 1); - if (!unit) - return -ENOMEM; + unit = uvc_alloc_new_entity(dev, UVC_EXT_GPIO_UNIT, + UVC_EXT_GPIO_UNIT_ID, 0, 1); + if (IS_ERR(unit)) + return PTR_ERR(unit);

unit->gpio.gpio_privacy = gpio_privacy; unit->gpio.irq = irq; diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index 70dc80e2b213dff333665022b3410b175d072793..881bfa0caab22714c26a3260cc843bda8e2706a4 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -41,6 +41,8 @@ #define UVC_EXT_GPIO_UNIT 0x7ffe #define UVC_EXT_GPIO_UNIT_ID 0x100

+#define UVC_INVALID_ENTITY_ID 0xffff + /* ------------------------------------------------------------------------ * Driver specific constants. */

--- base-commit: a75b8d198c55e9eb5feb6f6e155496305caba2dc change-id: 20250820-uvc-thadeu2-25723a961bd8

Best regards,