Hello Alistair Popple,
The patch 828fe4085cae: "mmu_notifiers: rename invalidate_range
notifier" from Jul 19, 2023 (linux-next), leads to the following
Smatch static checker warning:
mm/mmu_notifier.c:1020 mmu_interval_notifier_insert_locked()
error: NULL dereference inside function __mmu_notifier_register()
mm/mmu_notifier.c:671 __mmu_notifier_register()
warn: variable dereferenced before check 'subscription' (see line 624)
mm/mmu_notifier.c
1010 unsigned long start, unsigned long length,
1011 const struct mmu_interval_notifier_ops *ops)
1012 {
1013 struct mmu_notifier_subscriptions *subscriptions =
1014 mm->notifier_subscriptions;
1015 int ret;
1016
1017 mmap_assert_write_locked(mm);
1018
1019 if (!subscriptions || !subscriptions->has_itree) {
--> 1020 ret = __mmu_notifier_register(NULL, mm);
subscription is NULL here
1021 if (ret)
1022 return ret;
1023 subscriptions = mm->notifier_subscriptions;
1024 }
1025 return __mmu_interval_notifier_insert(interval_sub, mm, subscriptions,
1026 start, length, ops);
1027 }
regards,
dan carpenter
