linux-kernel - Re: [syzbot] [input?] [usb?] KMSAN: uninit-value in asus_report

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Date: Fri, 31 May 2024 11:53:29 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc: Edward Adam Davis <eadavis@...com>,
	syzbot+07762f019fd03d01f04c@...kaller.appspotmail.com,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
	Dan Carpenter <error27@...il.com>
Subject: Re: [syzbot] [input?] [usb?] KMSAN: uninit-value in asus_report_fixup

On Thu, May 30, 2024 at 08:16:59PM +0530, Harshit Mogalapalli wrote:
> > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> > index a90ed2ceae84..9f0e09f667b1 100644
> > --- a/drivers/hid/usbhid/hid-core.c
> > +++ b/drivers/hid/usbhid/hid-core.c
> > @@ -1029,7 +1029,7 @@ static int usbhid_parse(struct hid_device *hid)
> >   		return -EINVAL;
> >   	}
> > -	rdesc = kmalloc(rsize, GFP_KERNEL);
> > +	rdesc = kzalloc(rsize, GFP_KERNEL);

This kzalloc() is unnecessary because hid_get_class_descriptor() has
a memset() built in:

	memset(buf, 0, size);

I'm not a huge fan of how if hid_get_class_descriptor() runs out of
retries, we return the number of bytes in a partial read.  Then the
caller pretends it was a success instead of using the result.  But
that's a different issue.

regards,
dan carpenter