[PATCH] app/testpmd: fix segment fault with invalid queue id

[Stephen Hemminger]

On Tue, 16 May 2023 19:00:21 +0800
Dengdui Huang <huangdengdui at huawei.com> wrote:

> When input queue id is invalid, it will lead to
> Segmentation fault, like:
> 
> dpdk-testpmd -a 0000:01:00.0 -- -i
> testpmd> show port 0 txq/rxq 99 desc 0 status  
> Segmentation fault
> 
> dpdk-testpmd -a 0000:01:00.0 -- -i
> testpmd> show port 0 rxq 99 desc used count  
> Segmentation fault
> 
> This patch fixes it.
> 
> In addition, this patch add the check for the offset
> of the descriptor in case of other anomalies.
> 
> Fixes: fae9aa717d6c ("app/testpmd: support checking descriptor status")
> Fixes: 3f9acb5c83bb ("ethdev: avoid non-dataplane checks in Rx queue count")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Dengdui Huang <huangdengdui at huawei.com>

What is the backtrace and device driver?  The problem is that other users
besides testpmd might hit same problem.

It would make sense to have a function to test for valid rx and tx queue id
in rte_ethdev. Similar to existing rte_eth_dev_is_valid_port() rather than
open coding it.  Maybe rte_eth_dev_is_valid_rxq(port_id, queue_id)?

here was talk that the existing rx queue descriptor status is racy, and
unused by any real application; and therefore would be good candidate for
future removal.