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From:   SeongJae Park <sj@kernel.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     SeongJae Park <sj@kernel.org>, damon@lists.linux.dev,
        linux-mm@kvack.org, stable@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] mm/damon/core: initialize damo_filter->list from damos_new_filter()
Date:   Sat, 29 Jul 2023 20:37:32 +0000
Message-Id: <20230729203733.38949-2-sj@kernel.org>
In-Reply-To: <20230729203733.38949-1-sj@kernel.org>
References: <20230729203733.38949-1-sj@kernel.org>
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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().

Fixes: 98def236f63c ("mm/damon/core: implement damos filter")
Cc: stable@vger.kernel.org # 6.3.x-
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 91cff7f2997e..eb9580942a5c 100644
--- 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;
 }
 
-- 
2.25.1