Re: [PATCH][next] Drivers: hv: vmbus: Use struct_size() helper in kmalloc()

[Wei Liu]

On Thu, Jan 27, 2022 at 04:01:28PM +0000, Michael Kelley (LINUX) wrote:
> From: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> Sent: Tuesday, January 25, 2022 10:02 AM
> > 
> > Make use of the struct_size() helper instead of an open-coded version,
> > in order to avoid any potential type mistakes or integer overflows that,
> > in the worst scenario, could lead to heap overflows.
> > 
> > Also, address the following sparse warnings:
> > drivers/hv/vmbus_drv.c:1132:31: warning: using sizeof on a flexible structure
> > 
> > Link: https://github.com/KSPP/linux/issues/174
> > ---
> >  drivers/hv/vmbus_drv.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index 17bf55fe3169..cd193456cd84 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -1129,7 +1129,7 @@ void vmbus_on_msg_dpc(unsigned long data)
> >  	}
> > 
> >  	if (entry->handler_type	== VMHT_BLOCKING) {
> > -		ctx = kmalloc(sizeof(*ctx) + payload_size, GFP_ATOMIC);
> > +		ctx = kmalloc(struct_size(ctx, msg.payload, payload_size), GFP_ATOMIC);
> >  		if (ctx == NULL)
> >  			return;
> > 
> > --
> > 2.27.0
> 
> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> 

Applied to hyperv-next. Thanks.