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

Matan Azrad matan at mellanox.com
Tue Aug 6 10:19:01 CEST 2019



From: Stephen Hemminger
> On Sun, 4 Aug 2019 08:31:54 +0000
> Matan Azrad <matan at mellanox.com> wrote:
> 
> > > > >  	/* 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?
> 
> I don't think 32 bit build is that well tested. But yes a mask needs to hold 64
> ports.

What if someone changes RTE_MAX_ETHPORTS to be bigger than 64 in config file?

Assume the user changes RTE_MAX_ETHPORTS to 128, and there is a valid port in range [64, 127].
Then,  assume the failsafe sub device owns port ID 0.

Because the mask bits are not enough to handle the above range, you will get port 0 as valid port - bug.

I think you need one more check to the RTE_MAX_ETHPORTS > 64 case. 


> > > 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:
> 
> The problem  here was my mistake for not having wide enough portmask.



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