[PATCH v4 3/9] media: uvcvideo: Allow entities with no pads

From: Ricardo Ribalda
Date: Tue Dec 15 2020 - 10:52:55 EST


Avoid an underflow while calculating the number of inputs for entities
with zero pads.

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
drivers/media/usb/uvc/uvc_driver.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 9f4451a2e0a6..534629ecd60d 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1033,7 +1033,11 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id,
unsigned int i;

extra_size = roundup(extra_size, sizeof(*entity->pads));
- num_inputs = (type & UVC_TERM_OUTPUT) ? num_pads : num_pads - 1;
+ if (num_pads)
+ num_inputs = (type & UVC_TERM_OUTPUT) ? num_pads :
+ num_pads - 1;
+ else
+ num_inputs = 0;
size = sizeof(*entity) + extra_size + sizeof(*entity->pads) * num_pads
+ num_inputs;
entity = kzalloc(size, GFP_KERNEL);
@@ -1066,7 +1070,7 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id,

for (i = 0; i < num_inputs; ++i)
entity->pads[i].flags = MEDIA_PAD_FL_SINK;
- if (!UVC_ENTITY_IS_OTERM(entity))
+ if (!UVC_ENTITY_IS_OTERM(entity) && num_pads)
entity->pads[num_pads-1].flags = MEDIA_PAD_FL_SOURCE;

entity->bNrInPins = num_inputs;
--
2.29.2.684.gfbc64c5ab5-goog