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SubjectRe: [PATCH][netlabel] Don't risk NULL ptr deref in netlbl_unlabel_staticlist_gen() if ifindex not found
On 16/04/2008, Paul Moore <paul.moore@hp.com> wrote:
> On Wednesday 16 April 2008 5:08:58 pm Jesper Juhl wrote:
> > Hi,
> >
> > dev_get_by_index() may return NULL if nothing is found. In
> > net/netlabel/netlabel_unlabeled.c::netlbl_unlabel_staticlist_gen()
> > the function is called, but the return value is never checked. If it
> > returns NULL then we'll deref a NULL pointer on the very next line.
> > I checked the callers, and I don't think this can actually happen
> > today, but code changes over time and in the future it might happen
> > and it does no harm to be defensive and check for the failure, so
> > that if/when it happens we'll fail gracefully instead of crashing.
> >
> > Please consider the patch below for inclusion.
> >
> >
> > Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
>
>
> I agree we should check for NULL here. I checked the return of
> dev_get_by_index() in the rest of the file I must have just forgotten
> to check it here.
>
> Thanks for finding this and fixing it.
>
You're welcome.

> Acked-by: Paul Moore <paul.moore@hp.com>
>

David, will you merge this in the net tree ?

>
> >
> > netlabel_unlabeled.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/net/netlabel/netlabel_unlabeled.c
> > b/net/netlabel/netlabel_unlabeled.c index 4478f2f..6af9457 100644
> > --- a/net/netlabel/netlabel_unlabeled.c
> > +++ b/net/netlabel/netlabel_unlabeled.c
> > @@ -1339,6 +1339,10 @@ static int netlbl_unlabel_staticlist_gen(u32
> > cmd,
> >
> > if (iface->ifindex > 0) {
> > dev = dev_get_by_index(&init_net, iface->ifindex);
> > + if (!dev) {
> > + ret_val = -ENODEV;
> > + goto list_cb_failure;
> > + }
> > ret_val = nla_put_string(cb_arg->skb,
> > NLBL_UNLABEL_A_IFACE, dev->name);
> > dev_put(dev);
>

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html


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