Re: [PATCH v2] lib/ethdev: fix segfault in secondary process by validating dev_private pointer

[Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>]

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Secondary application not only breaking on device closing,
it's also getting segfault when we do "show device info all" from secondary
after primary closes:

testpmd> show device info all

********************* Infos for device 0000:03:00.0 *********************
Bus name: pci
Bus information: vendor_id=15b3, device_id=101d
Driver name: mlx5_pci
Devargs:
Connect to socket: 0

Segmentation fault (core dumped)

This patch prevents these crashes and it seems that these fixes should
be in PMD along with the ethdev layer. Some more checks will be added
in the next version to prevent "show device info all" crash.



On Wed, Jul 23, 2025 at 9:50 AM Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>
wrote:

> In secondary processes, directly accessing 'dev->data->dev_private' can
> cause a segmentation fault if the primary process has exited or if the
> shared memory is no longer accessible.
>
> This patch adds a safety check using rte_mem_virt2phy(), with an
> unlikely() branch hint to minimize performance impact in the fast path.
> This ensures 'dev_private' is still valid before accessing it.
>
> Fixes: bdad90d12ec8 ("ethdev: change device info get callback to return
> int")
> Cc: stable@dpdk.org
>
> Signed-off-by: Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>
> ---
>  lib/ethdev/rte_ethdev.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index dd7c00bc94..ef5dc55f2e 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -4079,6 +4079,13 @@ rte_eth_dev_info_get(uint16_t port_id, struct
> rte_eth_dev_info *dev_info)
>
>         if (dev->dev_ops->dev_infos_get == NULL)
>                 return -ENOTSUP;
> +       if (rte_eal_process_type() == RTE_PROC_SECONDARY &&
> +               unlikely(rte_mem_virt2phy(dev->data->dev_private) ==
> RTE_BAD_PHYS_ADDR)) {
> +                       RTE_ETHDEV_LOG_LINE(ERR,
> +                       "Secondary: dev_private not accessible (primary
> exited?)");
> +                       rte_errno = ENODEV;
> +                       return -rte_errno;
> +       }
>         diag = dev->dev_ops->dev_infos_get(dev, dev_info);
>         if (diag != 0) {
>                 /* Cleanup already filled in device information */
> --
> 2.43.0
>
>

-- 
Engr. Khadem Ullah,
Software Engineer,
Dreambig Semiconductor Inc
https://dreambigsemi.com/

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