Messages in this thread | | | Subject | RE: [PATCH] Clean console safely | Date | Wed, 13 Apr 2011 16:55:01 -0700 | From | "Daniel Taylor" <> |
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> -----Original Message----- > From: linux-kernel-owner@vger.kernel.org > [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Chris Ball > Sent: Wednesday, April 13, 2011 8:45 AM > To: Greg Kroah-Hartman > Cc: Alan Cox; linux-kernel@vger.kernel.org; Artem Bityutskiy > Subject: Re: [PATCH] Clean console safely > > Hi, > > On Wed, Apr 13 2011, Petr Pisar wrote: > > On Wed, Apr 13, 2011 at 11:18:04AM -0400, Chris Ball wrote: > >> > >> On Wed, Apr 13 2011, Petr Písař wrote: > >> > Traditional \E[2J sequence erases console display but scroll-back > >> > buffer and underlying device (frame) buffer keep data that can be > >> > accessed by scrolling console back. > >> > > >> > This patch introduce new \E[J parameter 3 that allows to scramble > >> > scroll-back buffer explicitly. Session locking programs (screen, > >> > vlock) can use it to prevent attacker to browse locked console > >> > history. > >> > > >> > Signed-off-by: Petr Písař <ppisar@redhat.com> > >> > --- > >> > drivers/tty/vt/vt.c | 6 ++++++ > >> > 1 files changed, 6 insertions(+), 0 deletions(-) > >> > > >> > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > >> > index 4bea1ef..fe96a1f 100644 > >> > --- a/drivers/tty/vt/vt.c > >> > +++ b/drivers/tty/vt/vt.c > >> > @@ -1197,6 +1197,12 @@ static void csi_J(struct vc_data > *vc, int vpar) > >> > vc->vc_x + 1); > >> > } > >> > break; > >> > + case 3: /* erase scroll-back buffer > (and whole display) */ > >> > + scr_memsetw(vc->vc_screenbuf, > vc->vc_video_erase_char, > >> > + vc->vc_screenbuf_size >> 1); > >> > + set_origin(vc); > >> > + if (CON_IS_VISIBLE(vc)) > >> > + update_screen(vc); > >> > case 2: /* erase whole display */ > >> > count = vc->vc_cols * vc->vc_rows; > >> > start = (unsigned short *)vc->vc_origin; > >> > >> Nitpick: the cases were ordered before -- 3 should go after 2. > >> > > This is on purpose to continue with code for case 2 as it > prepares variables > > for cleaning visible part of display after the switch block. > > Oops, sorry; I saw an imaginary break statement there.
Shouldn't there be a "/* fall through */", or similar, comment, or all of the existing ones in the kernel extraneous? Personally, I prefer to see clearly that the missing "break" is intentional.
> > - Chris. > -- > Chris Ball <cjb@laptop.org> <http://printf.net/> > One Laptop Per Child > -- > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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