Messages in this thread | | | Date | Tue, 22 Feb 2022 07:56:13 +0100 | Subject | Re: [PATCH] vt_ioctl: fix potential spectre v1 in VT_DISALLOCATE | From | Jiri Slaby <> |
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On 22. 02. 22, 4:56, Xiaomeng Tong wrote: > In VT_ACTIVATE an almost identical code path has been patched > with array_index_nospec. In the VT_DISALLOCATE path, the arg is > the user input from a system call argument and lately used as a index > for vc_cons[index].d access, which can be reached through path like > vt_disallocate->vc_busy or vt_disallocate->vc_deallocate. > For consistency both code paths should have the same mitigations > applied. > > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> > --- > drivers/tty/vt/vt_ioctl.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c > index 580136986..acd53c1c9 100644 > --- a/drivers/tty/vt/vt_ioctl.c > +++ b/drivers/tty/vt/vt_ioctl.c > @@ -898,10 +898,13 @@ int vt_ioctl(struct tty_struct *tty, > if (arg > MAX_NR_CONSOLES) > return -ENXIO; > > - if (arg == 0) > + if (arg == 0) { > vt_disallocate_all();
Could you add a break; here and remove the else branching completely?
> - else > - return vt_disallocate(--arg); > + } else { > + --arg; > + arg = array_index_nospec(arg, MAX_NR_CONSOLES); You could simply do: arg = array_index_nospec(arg - 1, MAX_NR_CONSOLES); and remove --arg; completely.
> + return vt_disallocate(arg); > + } > break;
When you do the above, this break is superfluous.
thanks, -- js suse labs
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