mm/damon/core: initialize damo_filter->list from damos_new_filter()

damos_new_filter() is not initializing the list field of newly allocated
filter object.  However, DAMON sysfs interface and DAMON_RECLAIM are not
initializing it after calling damos_new_filter().  As a result, accessing
uninitialized memory is possible.  Actually, adding multiple DAMOS filters
via DAMON sysfs interface caused NULL pointer dereferencing.  Initialize
the field just after the allocation from damos_new_filter().

Link: https://lkml.kernel.org/r/20230729203733.38949-2-sj@kernel.org
Fixes: 98def236f63c ("mm/damon/core: implement damos filter")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 91cff7f..eb95809 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -273,6 +273,7 @@ struct damos_filter *damos_new_filter(enum damos_filter_type type,
                return NULL;
        filter->type = type;
        filter->matching = matching;
+       INIT_LIST_HEAD(&filter->list);
        return filter;
 }