[PATCH] arm_mpam: guard MBWU state before adding it to garbage

[Guangshuo Li]

__destroy_component_cfg() adds each RIS mbwu_state object to the MPAM
garbage list when destroying component configuration.

However, mbwu_state is allocated per RIS and only for RISes with MBWU
monitors. A component can therefore have comp->cfg allocated while some
RISes still have ris->mbwu_state set to NULL.

Passing a NULL mbwu_state to add_to_garbage() dereferences the NULL
pointer inside the macro.

Skip RISes that do not have an mbwu_state object before adding them to
the garbage list.

Fixes: 41e8a14950e1 ("arm_mpam: Track bandwidth counter state for power management")
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 drivers/resctrl/mpam_devices.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index b69f99488111..59225694255f 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -2606,8 +2606,10 @@ static void __destroy_component_cfg(struct mpam_component *comp)
 		msc = vmsc->msc;
 
 		if (mpam_mon_sel_lock(msc)) {
-			list_for_each_entry(ris, &vmsc->ris, vmsc_list)
-				add_to_garbage(ris->mbwu_state);
+			list_for_each_entry(ris, &vmsc->ris, vmsc_list) {
+				if (ris->mbwu_state)
+					add_to_garbage(ris->mbwu_state);
+			}
 			mpam_mon_sel_unlock(msc);
 		}
 	}
-- 
2.43.0