On Mon, 2008-10-27 at 18:54 -0700, Andrew Morton wrote:
> On Tue, 28 Oct 2008 10:14:30 +0900 Ian Kent <raven@xxxxxxxxxx> 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!
>
> 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.
Ian
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