Re: [PATCH net-next v2 1/2] devlink: param: do not dereference a missing param item

[Ivan Vecera <ivecera@redhat.com>]

On 11/2/26 14:15, Linkui Xiao wrote:
> From: Linkui Xiao <xiaolinkui@kylinos.cn>
> 
> devl_param_value_changed() looks the param item up by id and only warns
> when the lookup fails. devlink_param_notify() is called with the result
> regardless, and devlink_nl_param_fill() dereferences param_item->param
> in its very first statement, so a driver that passes a param_id which is
> not registered on this instance turns the warning into a NULL pointer
> dereference.
> 
> Every other user of devlink_param_find_by_id() handles the NULL result:
> devlink_param_unregister() and devl_param_driverinit_value_set() return
> right after the same warning, devl_param_driverinit_value_get() returns
> -EINVAL. Do the same here so that a bogus param_id costs a warning
> instead of an oops.
> 
> Fixes: ea601e170988 ("devlink: Add devlink notifications support for params")
> Signed-off-by: Linkui Xiao <xiaolinkui@kylinos.cn>
> Reviewed-by: Simon Horman <horms@kernel.org>
> Link: https://lore.kernel.org/all/20230126075838.1643665-5-jiri@resnulli.us/
> Link: https://lore.kernel.org/r/20261030033332.3685172-2-xiaolinkui@126.com
> ---
> v2: reposted against net-next at Simon's suggestion; no code change.
Reviewed-by: Ivan Vecera <ivecera@redhat.com>