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Subject[PATCH] quickcam_messenger.c: possible buffer overflow while use strncat.
Date
	In driver ./drivers/media/video/usbvideo/quickcam_messenger.c in line 91:
91 usb_make_path(dev, cam->input_physname, sizeof(cam-
>input_physname));
After this line we use strncat:
92 strncat(cam->input_physname, "/input0", sizeof(cam-
>input_physname));
where sizeof(cam->input_physname) returns length of cam->input_phisname
without length for null-symbol. But this parameter must be - "maximum numbers
of bytes to copy", i.e.: sizeof(cam->input_physname)-strlen(cam-
>input_physname)-1.
In this case, after call to usb_make_path the similar drivers use strlcat.
Like in: drivers/hid/usbhid/hid-core.c:
1152 usb_make_path(dev, hid->phys, sizeof(hid->phys));
1153 strlcat(hid->phys, "/input", sizeof(hid->phys));

Found by Linux Driver Verification Project.

Use strlcat instead of strncat.

Signed-off-by:Alexander Strakh <strakh@ispras.ru>

---
diff --git a/./a/drivers/media/video/usbvideo/quickcam_messenger.c
b/./b/drivers/media/video/usbvideo/quickcam_messenger.c
index 803d3e4..c4d1b96 100644
--- a/./a/drivers/media/video/usbvideo/quickcam_messenger.c
+++ b/./b/drivers/media/video/usbvideo/quickcam_messenger.c
@@ -89,7 +89,7 @@ static void qcm_register_input(struct qcm *cam, struct
usb_device *dev)
int error;

usb_make_path(dev, cam->input_physname, sizeof(cam->input_physname));
- strncat(cam->input_physname, "/input0", sizeof(cam->input_physname));
+ strlcat(cam->input_physname, "/input0", sizeof(cam->input_physname));

cam->input = input_dev = input_allocate_device();
if (!input_dev) {


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