Re: [PATCH 10/12] net: sctp: avoid incorrect time_t use

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Wed, Sep 30, 2015 at 09:57:31AM -0400, Neil Horman wrote:
> On Wed, Sep 30, 2015 at 01:26:40PM +0200, Arnd Bergmann wrote:
> > We want to avoid using time_t in the kernel because of the y2038
> > overflow problem. The use in sctp is not for storing seconds at
> > all, but instead uses microseconds and is passed as 32-bit
> > on all machines.
> > 
> > This patch changes the type to u32, which better fits the use.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > Cc: Vlad Yasevich <vyasevich@gmail.com>
> > Cc: Neil Horman <nhorman@tuxdriver.com>
> > Cc: linux-sctp@vger.kernel.org
> > ---
> >  net/sctp/sm_make_chunk.c | 2 +-
> >  net/sctp/sm_statefuns.c  | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> > index 7954c52e1794..763e06a55155 100644
> > --- a/net/sctp/sm_make_chunk.c
> > +++ b/net/sctp/sm_make_chunk.c
> > @@ -2494,7 +2494,7 @@ static int sctp_process_param(struct sctp_association *asoc,
> >  	__u16 sat;
> >  	int retval = 1;
> >  	sctp_scope_t scope;
> > -	time_t stale;
> > +	u32 stale;
> >  	struct sctp_af *af;
> >  	union sctp_addr_param *addr_param;
> >  	struct sctp_transport *t;
> > diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> > index d7eaa7354cf7..6f46aa16cb76 100644
> > --- a/net/sctp/sm_statefuns.c
> > +++ b/net/sctp/sm_statefuns.c
> > @@ -2306,7 +2306,7 @@ static sctp_disposition_t sctp_sf_do_5_2_6_stale(struct net *net,
> >  						 sctp_cmd_seq_t *commands)
> >  {
> >  	struct sctp_chunk *chunk = arg;
> > -	time_t stale;
> > +	u32 stale;
> >  	sctp_cookie_preserve_param_t bht;
> >  	sctp_errhdr_t *err;
> >  	struct sctp_chunk *reply;
> > -- 
> > 2.1.0.rc2
> > 
> > 
> 
> Assignments to this variable use ntohl, won't this change risk overflow?
> 
> Neil

But isn't ntohl always 4 bytes long?

Marcelo