Re: [RFC] ethdev: add buffer size parameter to rte_eth_dev_get_name_by_port()

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Apr 09, 2026 at 09:59:04AM +0300, Andrew Rybchenko wrote:
> On 4/9/26 4:36 AM, Stephen Hemminger wrote:
> > rte_eth_dev_get_name_by_port() uses strcpy() into a caller-provided
> > buffer with no bounds checking. A mistaken caller that supplies a
> > buffer smaller than RTE_ETH_NAME_MAX_LEN can overflow the buffer.
> > 
> > Add a size parameter and replace strcpy() with strlcpy(), returning
> > -ERANGE if the name is truncated. The copy is now performed under
> > the ethdev shared data lock so that the name cannot be mutated by
> > another process between reading and copying.
> > 
> > The previous ABI is preserved via symbol versioning (DPDK_26) with a
> > thin wrapper that delegates to the new implementation with
> > RTE_ETH_NAME_MAX_LEN. The versioned symbol will be removed in 26.11.
> > 
> > Update all in-tree callers to pass sizeof(name) as the new parameter.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> 
> with notes below fixed
> 
> Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> 
> > diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> > index 2edc7a362e..586a56bd46 100644
> > --- a/lib/ethdev/rte_ethdev.c
> > +++ b/lib/ethdev/rte_ethdev.c
> > @@ -721,12 +721,9 @@ rte_eth_dev_count_total(void)
> >   	return count;
> >   }
> > -RTE_EXPORT_SYMBOL(rte_eth_dev_get_name_by_port)
> > -int
> > -rte_eth_dev_get_name_by_port(uint16_t port_id, char *name)
> > +static int
> > +eth_dev_get_name_by_port(uint16_t port_id, char *name, size_t size)
> >   {
> > -	char *tmp;
> > -
> >   	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> >   	if (name == NULL) {
> > @@ -735,19 +732,46 @@ rte_eth_dev_get_name_by_port(uint16_t port_id, char *name)
> >   		return -EINVAL;
> >   	}
> > +	if (size == 0) {
> > +		RTE_ETHDEV_LOG_LINE(ERR,
> > +			"Cannot get ethdev port %u name with zero-size buffer", port_id);
> > +		return -EINVAL;
> > +	}
> > +
> >   	rte_spinlock_lock(rte_mcfg_ethdev_get_lock());
> > -	/* shouldn't check 'rte_eth_devices[i].data',
> > -	 * because it might be overwritten by VDEV PMD */
> > -	tmp = eth_dev_shared_data->data[port_id].name;
> > +	/*
> > +	 * Use the shared data name rather than rte_eth_devices[].data->name
> > +	 * because VDEV PMDs may overwrite the per-process data pointer.
> > +	 */
> > +	size_t n = strlcpy(name, eth_dev_shared_data->data[port_id].name, size);
> 
> As far as I know typically variable declaration and code are not mixed
> in DPDK.
> 

AFAIK That used to be the case because early versions of DPDK targetting a
very early C standard. More recently, we've started allowing this sort of
use, which makes the code more readable IMHO and easier to work with too as
commenting out blocks when debugging leads to fewer unused variable warnings.

/Bruce