Hi Thadeu Take a look at checkpatch https://gitlab.freedesktop.org/linux-media/users/patchwork/-/jobs/63550656 , and the nit. After that feel free to add my Reviewed-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> On Thu, 12 Sept 2024 at 20:52, Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx> wrote: > > 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, > ``` > > So, deny allocating an entity with ID 0 or an ID that belongs to a unit > that is already added to the list of entities. > > 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> > > Reported-by: syzbot+0584f746fde3d52b4675@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=0584f746fde3d52b4675 > Reported-by: syzbot+dd320d114deb3f5bb79b@xxxxxxxxxxxxxxxxxxxxxxxxx > 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@xxxxxxxxxx> > --- > drivers/media/usb/uvc/uvc_driver.c | 70 ++++++++++++++++++------------ > 1 file changed, 43 insertions(+), 27 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > index f0febdc08c2d..3daa93a29776 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -775,14 +775,27 @@ 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; > nit: I'd swap the order of the checks, !id is a much simpler check than uvc_entity_by_id(). > + /* Per UVC 1.1+ spec 3.7.2, the ID is unique */ > + if (uvc_entity_by_id(dev, id)) { > + dev_err(&dev->udev->dev, "Found multiple Units with the same ID.\n"); > + return ERR_PTR(-EINVAL); > + } > + > + /* Per UVC 1.1+ spec 3.7.2, the ID should be non-zero */ > + if (id == 0) { > + dev_err(&dev->udev->dev, "Found Unit with invalid ID 0.\n"); > + return ERR_PTR(-EINVAL); > + } > + > extra_size = roundup(extra_size, sizeof(*entity->pads)); > if (num_pads) > num_inputs = type & UVC_TERM_OUTPUT ? num_pads : num_pads - 1; > @@ -792,7 +805,7 @@ 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; > @@ -904,10 +917,10 @@ 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]; > @@ -1016,10 +1029,10 @@ 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; > @@ -1075,10 +1088,10 @@ 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); > > @@ -1097,9 +1110,10 @@ 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); > > @@ -1119,9 +1133,9 @@ 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 = > @@ -1148,9 +1162,10 @@ 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]; > @@ -1290,9 +1305,10 @@ static int uvc_gpio_parse(struct uvc_device *dev) > return dev_err_probe(&dev->udev->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; > -- > 2.34.1 > -- Ricardo Ribalda
