On Tue, 2008-10-28 at 11:11 +0900, Ian Kent wrote:
> On Tue, 2008-10-28 at 11:07 +0900, Ian Kent wrote:
> > On Mon, 2008-10-27 at 18:54 -0700, Andrew Morton wrote:
> > > On Tue, 28 Oct 2008 10:14:30 +0900 Ian Kent <[EMAIL PROTECTED]> wrote:
> > >
> > > > In a previous patch a comment was made that checking for the existence
> > > > of
> > > > a NULL terminator in strings copied from userspace wasn't needed as this
> > > > is done in many places in the kernel without problem. This patch removes
> > > > this string terminator check.
> > > >
> > >
> > > ah, OK. Now I'm worried.
> > >
> > > >
> > > > fs/autofs4/dev-ioctl.c | 20 --------------------
> > > > 1 files changed, 0 insertions(+), 20 deletions(-)
> > > >
> > > > diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
> > > > index 625abf5..304c1ff 100644
> > > > --- a/fs/autofs4/dev-ioctl.c
> > > > +++ b/fs/autofs4/dev-ioctl.c
> > > > @@ -51,18 +51,6 @@ static int check_name(const char *name)
> > > > }
> > > >
> > > > /*
> > > > - * Check a string doesn't overrun the chunk of
> > > > - * memory we copied from user land.
> > > > - */
> > > > -static int invalid_str(char *str, void *end)
> > > > -{
> > > > - while ((void *) str <= end)
> > > > - if (!*str++)
> > > > - return 0;
> > > > - return -EINVAL;
> > > > -}
> > > > -
> > > > -/*
> > > > * Check that the user compiled against correct version of autofs
> > > > * misc device code.
> > > > *
> > > > @@ -143,14 +131,6 @@ static int validate_dev_ioctl(int cmd, struct
> > > > autofs_dev_ioctl *param)
> > > > cmd);
> > > > goto out;
> > > > }
> > > > -
> > > > - err = invalid_str(param->path,
> > > > - (void *) ((size_t) param +
> > > > param->size));
> > > > - if (err) {
> > > > - AUTOFS_WARN("invalid path supplied for
> > > > cmd(0x%08x)",
> > > > - cmd);
> > > > - goto out;
> > > > - }
> > > > }
> > > >
> > > > err = 0;
> > >
> > > What will now happen if userspace passes in a non-null-terminated
> > > string (if that's possible)?
> > >
> > > Presumably that isn't possible, or it's never been tested, because
> > > before we check for null-termination we run check_name(), which
> > > _assumes_ null-termination!
>
> Oh .. hang on, point taken.
>
> > >
> > > The comment over validate_dev_ioctl() will need the "and is terminated"
> > > removed after this change, yes?
> >
> > Yes, but now I think I shouldn't have removed it.
> > For my part I would have been happy to keep this and now I think I
> > should so let's drop this patch.
Just to confirm.
Please drop this patch and I'll send a patch to fix the check order.
> >
> > Ian
> >
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