[PATCH] keys, dns: Fix size check of V1 server-list header

[Sedat Dilek]

On Mon, Jan 22, 2024 at 12:01 PM Sedat Dilek <sedat.dilek at gmail.com> wrote:
>
> On Mon, Jan 22, 2024 at 8:33 AM Petr Vorel <pvorel at suse.cz> wrote:
> >
> > From: Sedat Dilek <sedat.dilek at gmail.com>
> >
> > On Wed, Jan 10, 2024 at 10:12 PM David Howells <dhowells at redhat.com> wrote:
> > >
> > >
> > > Fix the size check added to dns_resolver_preparse() for the V1 server-list
> > > header so that it doesn't give EINVAL if the size supplied is the same as
> > > the size of the header struct (which should be valid).
> > >
> > > This can be tested with:
> > >
> > >         echo -n -e '\0\0\01\xff\0\0' | keyctl padd dns_resolver desc @p
> > >
> > > which will give "add_key: Invalid argument" without this fix.
> > >
> > > Fixes: 1997b3cb4217 ("keys, dns: Fix missing size check of V1 server-list header")
> >
> > [ CC stable at vger.kernel.org ]
> >
> > Your (follow-up) patch is now upstream.
> >
> > https://git.kernel.org/linus/acc657692aed438e9931438f8c923b2b107aebf9
> >
> > This misses CC: Stable Tag as suggested by Linus.
> >
> > Looks like linux-6.1.y and linux-6.6.y needs it, too.
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.6.11&id=da89365158f6f656b28bcdbcbbe9eaf97c63c474
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.72&id=079eefaecfd7bbb8fcc30eccb0dfdf50c91f1805
> >
> > BG,
> > -Sedat-
> >
> > Hi Greg, Sasa,
> >
> > could you please add this also to linux-6.1.y and linux-6.6.y?  (Easily
> > applicable to both, needed for both.) Or is there any reason why it's not
> > being added?
> >
>
> Great!
>
> I forgot to CC Greg and Sasha directly.
>
> Thanks.
>

Addendum:

Linus says:
"
Bah. Obvious fix is obvious.

Mind sending it as a proper patch with sign-off etc, and we'll get
this fixed and marked for stable.
"

https://lore.kernel.org/all/CAHk-=wiyG8BKKZmU7CDHC8+rmvBndrqNSgLV6LtuqN8W_gL3hA@mail.gmail.com/

-Sedat-

> BG,
> -Sedat-
>
> > Kind regards,
> > Petr
> >
> > > Reported-by: Pengfei Xu <pengfei.xu at intel.com>
> > > Link: https://lore.kernel.org/r/ZZ4fyY4r3rqgZL+4@xpf.sh.intel.com/
> > > Signed-off-by: David Howells <dhowells at redhat.com>
> > > cc: Edward Adam Davis <eadavis at qq.com>
> > > cc: Linus Torvalds <torvalds at linux-foundation.org>
> > > cc: Simon Horman <horms at kernel.org>
> > > Cc: Jarkko Sakkinen <jarkko at kernel.org>
> > > Cc: Jeffrey E Altman <jaltman at auristor.com>
> > > Cc: Wang Lei <wang840925 at gmail.com>
> > > Cc: Jeff Layton <jlayton at redhat.com>
> > > Cc: Steve French <sfrench at us.ibm.com>
> > > Cc: Marc Dionne <marc.dionne at auristor.com>
> > > Cc: "David S. Miller" <davem at davemloft.net>
> > > Cc: Eric Dumazet <edumazet at google.com>
> > > Cc: Jakub Kicinski <kuba at kernel.org>
> > > Cc: Paolo Abeni <pabeni at redhat.com>
> > > ---
> > >  net/dns_resolver/dns_key.c |    2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
> > > index f18ca02aa95a..c42ddd85ff1f 100644
> > > --- a/net/dns_resolver/dns_key.c
> > > +++ b/net/dns_resolver/dns_key.c
> > > @@ -104,7 +104,7 @@ dns_resolver_preparse(struct key_preparsed_payload *prep)
> > >                 const struct dns_server_list_v1_header *v1;
> > >
> > >                 /* It may be a server list. */
> > > -               if (datalen <= sizeof(*v1))
> > > +               if (datalen < sizeof(*v1))
> > >                         return -EINVAL;
> > >
> > >                 v1 = (const struct dns_server_list_v1_header *)data;
> > >
> > >
> >