Re: [dpdk-dev] [PATCH v5 1/4] examples/multi_process/client_server_mp: check port validity

[Matan Azrad <matan@mellanox.com>]

Hi Stephen

From: Stephen Hemminger
> On Fri, 2 Aug 2019 05:33:20 +0000
> Matan Azrad <matan@mellanox.com> wrote:
> 
> > Hi Stephen
> >
> > One more small  comment inline
> >
> > From:  Stephen Hemminger
> > > Sent: Friday, August 2, 2019 5:58 AM
> > > To: dev@dpdk.org
> > > Cc: Stephen Hemminger <sthemmin@microsoft.com>
> > > Subject: [dpdk-dev] [PATCH v5 1/4]
> > > examples/multi_process/client_server_mp: check port validity
> > >
> > > From: Stephen Hemminger <sthemmin@microsoft.com>
> > >
> > > The mp_server incorrectly allows a port mask that included hidden
> > > ports and which later caused either lost packets or failed initialization.
> > >
> > > This fixes explicitly checking that each bit in portmask is a valid
> > > port before using it.
> > >
> > > Fixes: 5b7ba31148a8 ("ethdev: add port ownership")
> > > Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> > > ---
> > >  .../client_server_mp/mp_server/args.c         | 35 ++++++++++---------
> > >  .../client_server_mp/mp_server/args.h         |  2 +-
> > >  .../client_server_mp/mp_server/init.c         |  7 ++--
> > >  3 files changed, 22 insertions(+), 22 deletions(-)
> > >
> > > diff --git
> > > a/examples/multi_process/client_server_mp/mp_server/args.c
> > > b/examples/multi_process/client_server_mp/mp_server/args.c
> > > index b0d8d7665c85..fdc008b3d677 100644
> > > --- a/examples/multi_process/client_server_mp/mp_server/args.c
> > > +++ b/examples/multi_process/client_server_mp/mp_server/args.c
> > > @@ -10,6 +10,7 @@
> > >  #include <errno.h>
> > >
> > >  #include <rte_memory.h>
> > > +#include <rte_ethdev.h>
> > >  #include <rte_string_fns.h>
> > >
> > >  #include "common.h"
> > > @@ -41,31 +42,33 @@ usage(void)
> > >   * array variable
> > >   */
> > >  static int
> > > -parse_portmask(uint8_t max_ports, const char *portmask)
> > > +parse_portmask(const char *portmask)
> > >  {
> > >  	char *end = NULL;
> > >  	unsigned long pm;
> > > -	uint16_t count = 0;
> > > +	uint16_t id;
> > >
> > >  	if (portmask == NULL || *portmask == '\0')
> > >  		return -1;
> > >
> > >  	/* convert parameter to a number and verify */
> > >  	pm = strtoul(portmask, &end, 16);
> > > -	if (end == NULL || *end != '\0' || pm == 0)
> > > +	if (end == NULL || *end != '\0' || pm > UINT16_MAX || pm == 0)
> >
> > Why pm > UINT16_MAX ? should be something like > (1 <<
> RTE_MAX_ETHPORTS) - 1.
> > And need to be sure pm type can hold RTE_MAX_ETHPORTS bits,
> otherwise port 0 may unlikely be all the time visible in the loop below.
> >
> 
> The DPDK assumes a lot of places that unsigned long will hold a port mask.

So, all are bugs, no?

> If some extra bits are set, the error is visible later when the bits are leftover
> after finding ports.

Yes, but if there is a valid port which its port id is bigger than the portmask bits number - port 0 will be all the time visible in the check -> bug.

> The original code had worse problems, it would not catch invalid pm values at
> all and truncate silently.

Yes, maybe, but I really don't understand why you chose to limit for 16 ports, where this number come from?
So, my approach here, 2 options:

1. Remove this line change at all.
2. Do the portmask check bug-free.

Matan