Re: [PATCH v2 3/3] libsepol: assure string NUL-termination of ibdev_name

From: Nicolas Iooss <nicolas.iooss@m4x.org>
To: "Christian Göttsche" <cgzones@googlemail.com>
Cc: SElinux list <selinux@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] libsepol: assure string NUL-termination of ibdev_name
Date: Tue, 13 Jul 2021 21:59:47 +0200	[thread overview]
Message-ID: <CAJfZ7=k-cBU3D72aWZ2k2FgMvxqpNMv5gvC=i+UNowW5StXikA@mail.gmail.com> (raw)
In-Reply-To: <CAJfZ7==-in9CtKJwagwFV3btKt2KqfLQQ9v2Tu75VdN18cYOJA@mail.gmail.com>

On Mon, Jul 12, 2021 at 9:35 AM Nicolas Iooss <nicolas.iooss@m4x.org> wrote:
>
> On Thu, Jul 1, 2021 at 8:07 PM Christian Göttsche
> <cgzones@googlemail.com> wrote:
> >
> > Clang complains:
> >
> >     ibendport_record.c: In function ‘sepol_ibendport_get_ibdev_name’:
> >     ibendport_record.c:169:2: error: ‘strncpy’ specified bound 64 equals destination size [-Werror=stringop-truncation]
> >       169 |  strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX);
> >           |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >     ibendport_record.c: In function ‘sepol_ibendport_set_ibdev_name’:
> >     ibendport_record.c:189:2: error: ‘strncpy’ specified bound 64 equals destination size [-Werror=stringop-truncation]
> >       189 |  strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX);
> >           |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > strncpy(3) does not NUL-terminate the destination if the source is of
> > the same length or longer then the specified size.
> > The source of these copies are retrieved from
> > sepol_ibendport_alloc_ibdev_name(), which allocates a fixed amount of
> > IB_DEVICE_NAME_MAX bytes.
> > Reduce the size to copy by 1 of all memory regions allocated by
> > sepol_ibendport_alloc_ibdev_name().
> >
> > Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
>
> Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
>
> Thanks,
> Nicolas

Merged.
Thanks!
Nicolas

> > ---
> > v2:
> >   - use at all affected places as pointed out by James Carter
> >
> >  libsepol/src/ibendport_record.c | 8 ++++----
> >  libsepol/src/ibendports.c       | 2 +-
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/libsepol/src/ibendport_record.c b/libsepol/src/ibendport_record.c
> > index adf67161..1eb50914 100644
> > --- a/libsepol/src/ibendport_record.c
> > +++ b/libsepol/src/ibendport_record.c
> > @@ -62,7 +62,7 @@ int sepol_ibendport_key_create(sepol_handle_t *handle,
> >         if (sepol_ibendport_alloc_ibdev_name(handle, &tmp_key->ibdev_name) < 0)
> >                 goto err;
> >
> > -       strncpy(tmp_key->ibdev_name, ibdev_name, IB_DEVICE_NAME_MAX);
> > +       strncpy(tmp_key->ibdev_name, ibdev_name, IB_DEVICE_NAME_MAX - 1);
> >         tmp_key->port = port;
> >
> >         *key_ptr = tmp_key;
> > @@ -166,7 +166,7 @@ int sepol_ibendport_get_ibdev_name(sepol_handle_t *handle,
> >         if (sepol_ibendport_alloc_ibdev_name(handle, &tmp_ibdev_name) < 0)
> >                 goto err;
> >
> > -       strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX);
> > +       strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX - 1);
> >         *ibdev_name = tmp_ibdev_name;
> >         return STATUS_SUCCESS;
> >
> > @@ -186,7 +186,7 @@ int sepol_ibendport_set_ibdev_name(sepol_handle_t *handle,
> >         if (sepol_ibendport_alloc_ibdev_name(handle, &tmp) < 0)
> >                 goto err;
> >
> > -       strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX);
> > +       strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX - 1);
> >         free(ibendport->ibdev_name);
> >         ibendport->ibdev_name = tmp;
> >         return STATUS_SUCCESS;
> > @@ -230,7 +230,7 @@ int sepol_ibendport_clone(sepol_handle_t *handle,
> >         if (sepol_ibendport_alloc_ibdev_name(handle, &new_ibendport->ibdev_name) < 0)
> >                 goto omem;
> >
> > -       strncpy(new_ibendport->ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX);
> > +       strncpy(new_ibendport->ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX - 1);
> >         new_ibendport->port = ibendport->port;
> >
> >         if (ibendport->con &&
> > diff --git a/libsepol/src/ibendports.c b/libsepol/src/ibendports.c
> > index 6d56c9a1..ee5cb193 100644
> > --- a/libsepol/src/ibendports.c
> > +++ b/libsepol/src/ibendports.c
> > @@ -34,7 +34,7 @@ static int ibendport_from_record(sepol_handle_t *handle,
> >                                            &ibdev_name) < 0)
> >                 goto err;
> >
> > -       strncpy(tmp_ibendport->u.ibendport.dev_name, ibdev_name, IB_DEVICE_NAME_MAX);
> > +       strncpy(tmp_ibendport->u.ibendport.dev_name, ibdev_name, IB_DEVICE_NAME_MAX - 1);
> >
> >         free(ibdev_name);
> >         ibdev_name = NULL;
> > --
> > 2.32.0
> >