Re: [PATCH net 0/2] devlink: do not dereference a missing param item or shared buffer

[Linkui Xiao <xiaolinkui@126.com>]

Hi Simon,

thanks for the review.

On 2026/11/2 20:05, Simon Horman wrote:
> On Fri, Oct 30, 2026 at 11:33:30AM +0800, Linkui Xiao wrote:
>> From: Linkui Xiao <xiaolinkui@kylinos.cn>
>>
>> Two devlink helpers look an object up by id or index, warn when the
>> lookup fails, and then pass the NULL result to code that dereferences
>> it. A driver mistake (a param_id that was never registered, an sb_index
>> that was never registered or is unregistered twice) therefore costs an
>> oops instead of a warning.
>>
>>    1/2 param: devl_param_value_changed() hands the missing param item to
>>        devlink_param_notify() -> devlink_nl_param_fill(), whose first
>>        statement dereferences param_item->param.
>>
>>    2/2 sb: devl_sb_unregister() runs list_del() on the missing shared
>>        buffer; list is the first member of struct devlink_sb, so it
>>        reads and writes through address 0.
>>
>> In both cases every other user of the same lookup already returns right
>> after the warning, so the fixes just align the remaining callers; there
>> is no change of behavior beyond avoiding the dereference. The param side
>> follows the example Jiri set for devlink_param_unregister():
>>
>> Link: https://lore.kernel.org/all/20230126075838.1643665-5-jiri@resnulli.us/
>>
>> Both Fixes: tags point at the commits that introduced the unguarded
>> WARN_ON pattern; the current devl_() functions are pure renames of those
>> originals. No in-tree caller triggers either path today (the audit is
>> part of a defensive hardening pass), so both are aimed at stopping
>> out-of-tree drivers from turning a driver bug into an oops.
> 
> Thanks, both these fixes look good to me.
> 
> But I do wonder if the hardening aspect, from an in-tree pov,
> makes them net-next rather than net material.
> 
> I say that, because my understanding is that there is some pressure
> to only push critical bug fixes via net. This is because of the recent
> up-tick in bug fixes driven by AI-related activities.

Agreed -- net-next is open now, so I have just resent this as
[PATCH net-next v2 0/2]. Only the prefix and the base changed: the two 
hunks,
the Fixes: tags and the commit messages are the ones you reviewed, and the
Reviewed-by tags from v1 are kept. Neither patch carries a Cc: stable, so
there is nothing to drop with the new target.

Thanks,
Linkui