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SubjectRe: [PATCH v2 2/2] TTY: ntty, add one more sanity check
On Tue, Jun 07, 2011 at 06:57:50PM +0200, Jiri Slaby wrote:
> On 06/07/2011 06:44 PM, Greg KH wrote:
> > On Sun, Jun 05, 2011 at 02:16:17PM +0200, Jiri Slaby wrote:
> >> With the previous patch, we fixed another bug where read_buf was freed
> >> while we still was in n_tty_read. We currently check whether read_buf
> >> is NULL at the start of the function. Add one more check after we wake
> >> up from waiting for input.
> >>
> >> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> >> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
> >> ---
> >> drivers/tty/n_tty.c | 1 +
> >> 1 files changed, 1 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
> >> index 95d0a9c..c62c856 100644
> >> --- a/drivers/tty/n_tty.c
> >> +++ b/drivers/tty/n_tty.c
> >> @@ -1785,6 +1785,7 @@ do_it_again:
> >> break;
> >> }
> >> timeout = schedule_timeout(timeout);
> >> + BUG_ON(!tty->read_buf);
> >
> > So, if we ever hit this, what are we going to do with this crash?
> >
> > I really don't want to add more BUG_ON() calls to the kernel if at all
> > possible. Or is it the case that we will crash if this case is true
> > soon afterward anyway?
>
> Yeah, it will crash something like 10 lines below. The pointer is
> dereferenced there.

Ok, fair enough, thanks.

greg k-h


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