From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>,
	"# 6 . 18 . x" <stable@vger.kernel.org>,
	damon@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [PATCH 2/2] mm/damonn/lru_sort: handle ctx allocation failure
Date: Thu, 28 May 2026 17:01:03 -0700	[thread overview]
Message-ID: <20260529000104.7006-3-sj@kernel.org> (raw)
In-Reply-To: <20260529000104.7006-1-sj@kernel.org>

DAMON_LRU_SORT allocates the damon_ctx object for its kdamond in its
init function.  damon_lru_sort_enabled_store() wrongly assumes the
allocation will always succeed once tried.  If the damon_ctx allocation
was failed, therefore, code execution reaches to damon_commit_ctx()
while 'ctx' is NULL.  As a result, it dereferences the NULL 'ctx'
pointer.  Avoid the NULL dereference  by returning -ENOMEM if 'ctx' is
NULL.

Fixes: c4a8e662c839 ("mm/damon/lru_sort: use damon_initialized()")
Cc: <stable@vger.kernel.org> # 6.18.x
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/lru_sort.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index eca88ed941b32..8298c6001fd09 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -476,6 +476,10 @@ static int damon_lru_sort_enabled_store(const char *val,
 	if (!damon_initialized())
 		return 0;
 
+	/* damon_modules_new_paddr_ctx_target() in the init function failed. */
+	if (!ctx)
+		return -ENOMEM;
+
 	return damon_lru_sort_turn(enabled);
 }
 
-- 
2.47.3

     prev parent reply	other threads:[~2026-05-29  0:01 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-29  0:01 [PATCH 0/2] mm/damon/{reclaim,lru_sort}: handle ctx allocation failures SeongJae Park
2026-05-29  0:01 ` [PATCH 1/2] mm/damon/reclaim: handle ctx allocation failure SeongJae Park
2026-05-29  0:01 ` SeongJae Park [this message]

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