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

[Changwoo Min <changwoo@igalia.com>]

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@linux.intel.com>
Closes: https://lore.kernel.org/lkml/aXiySM79UYfk+ytd@ly-workstation/
Signed-off-by: Changwoo Min <changwoo@igalia.com>
---
 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);
-- 
2.53.0