Re: [PATCH] PM: EM: Fix null-ptr-deref in get-perf-domains when ID is not found

[Rafael J. Wysocki]

On Sun, Mar 29, 2026 at 9:36 AM Changwoo Min <changwoo@xxxxxxxxxx> wrote:
>
> dev_energymodel_nl_get_perf_domains_doit() calls
> em_perf_domain_get_by_id() but does not check the return value before
> passing it to __em_nl_get_pd_size(). When a caller supplies a
> non-existent perf domain ID, em_perf_domain_get_by_id() returns NULL,
> and __em_nl_get_pd_size() immediately dereferences pd->cpus
> (struct offset 0x30), causing a null-pointer dereference.
>
> The sister handler dev_energymodel_nl_get_perf_table_doit() already
> handles this correctly via __em_nl_get_pd_table_id(), which returns
> NULL and causes the caller to return -EINVAL. Add the same NULL check
> in the get-perf-domains do handler.
>
> Fixes: 380ff27af25e ("PM: EM: Add dump to get-perf-domains in the EM YNL spec")
> Reported-by: Yi Lai <yi1.lai@xxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/lkml/aXiySM79UYfk+ytd@ly-workstation/
> Signed-off-by: Changwoo Min <changwoo@xxxxxxxxxx>
> ---
>  kernel/power/em_netlink.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/power/em_netlink.c b/kernel/power/em_netlink.c
> index 5a611d3950fd..4d4fd29bd2be 100644
> --- a/kernel/power/em_netlink.c
> +++ b/kernel/power/em_netlink.c
> @@ -109,6 +109,8 @@ int dev_energymodel_nl_get_perf_domains_doit(struct sk_buff *skb,
>
>         id = nla_get_u32(info->attrs[DEV_ENERGYMODEL_A_PERF_DOMAIN_PERF_DOMAIN_ID]);
>         pd = em_perf_domain_get_by_id(id);
> +       if (!pd)
> +               return -EINVAL;
>
>         __em_nl_get_pd_size(pd, &msg_sz);
>         msg = genlmsg_new(msg_sz, GFP_KERNEL);
> --

Applied as 7.0-rc material, thanks!