From a15e17acce5aaae54243f55a7349c2225450b9bc Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 28 Sep 2022 13:19:21 -0700 Subject: usb: gadget: uvc: Fix argument to sizeof() in uvc_register_video() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When building s390 allmodconfig after commit 9b91a6523078 ("usb: gadget: uvc: increase worker prio to WQ_HIGHPRI"), the following error occurs: In file included from ../include/linux/string.h:253, from ../include/linux/bitmap.h:11, from ../include/linux/cpumask.h:12, from ../include/linux/smp.h:13, from ../include/linux/lockdep.h:14, from ../include/linux/rcupdate.h:29, from ../include/linux/rculist.h:11, from ../include/linux/pid.h:5, from ../include/linux/sched.h:14, from ../include/linux/ratelimit.h:6, from ../include/linux/dev_printk.h:16, from ../include/linux/device.h:15, from ../drivers/usb/gadget/function/f_uvc.c:9: In function ‘fortify_memset_chk’, inlined from ‘uvc_register_video’ at ../drivers/usb/gadget/function/f_uvc.c:424:2: ../include/linux/fortify-string.h:301:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 301 | __write_overflow_field(p_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This points to the memset() in uvc_register_video(). It is clear that the argument to sizeof() is incorrect, as uvc->vdev (a 'struct video_device') is being zeroed out but the size of uvc->video (a 'struct uvc_video') is being used as the third arugment to memset(). pahole shows that prior to commit 9b91a6523078 ("usb: gadget: uvc: increase worker prio to WQ_HIGHPRI"), 'struct video_device' and 'struct ucv_video' had the same size, meaning that the argument to sizeof() is incorrect semantically but there is no visible issue: $ pahole -s build/drivers/usb/gadget/function/f_uvc.o | grep -E "(uvc_video|video_device)\s+" video_device 1400 4 uvc_video 1400 3 After that change, uvc_video becomes slightly larger, meaning that the memset() will overwrite by 8 bytes: $ pahole -s build/drivers/usb/gadget/function/f_uvc.o | grep -E "(uvc_video|video_device)\s+" video_device 1400 4 uvc_video 1408 3 Fix the arugment to sizeof() so that there is no overwrite. Cc: stable@vger.kernel.org Fixes: e4ce9ed835bc ("usb: gadget: uvc: ensure the vdev is unset") Signed-off-by: Nathan Chancellor Reviewed-by: Laurent Pinchart Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20220928201921.3152163-1-nathan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_uvc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c index e6948cf8def3..836601227155 100644 --- a/drivers/usb/gadget/function/f_uvc.c +++ b/drivers/usb/gadget/function/f_uvc.c @@ -421,7 +421,7 @@ uvc_register_video(struct uvc_device *uvc) int ret; /* TODO reference counting. */ - memset(&uvc->vdev, 0, sizeof(uvc->video)); + memset(&uvc->vdev, 0, sizeof(uvc->vdev)); uvc->vdev.v4l2_dev = &uvc->v4l2_dev; uvc->vdev.v4l2_dev->dev = &cdev->gadget->dev; uvc->vdev.fops = &uvc_v4l2_fops; -- cgit v1.2.3-59-g8ed1b