Re: [PATCH] usb: gadget: storage: Fix Spectre v1 vulnerability

[Greg Kroah-Hartman]

On Tue, Oct 16, 2018 at 02:28:19PM +0300, Felipe Balbi wrote:
> 
> Hi Greg,
> 
> "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> writes:
> 
> > num can be indirectly controlled by user-space, hence leading to
> > a potential exploitation of the Spectre variant 1 vulnerability.
> >
> > This issue was detected with the help of Smatch:
> >
> > drivers/usb/gadget/function/f_mass_storage.c:3177 fsg_lun_make() warn:
> > potential spectre issue 'fsg_opts->common->luns' [r] (local cap)
> >
> > Fix this by sanitizing num before using it to index
> > fsg_opts->common->luns
> >
> > Notice that given that speculation windows are large, the policy is
> > to kill the speculation on the first load and not worry if it can be
> > completed with a dependent load/store [1].
> >
> > [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> 
> Can you still take this as an urgent fix?
> 
> Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxx>

Yes, will do so, thanks.

greg k-h

> 
> -- 
> balbi