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From:   Liam Ni <zhiguangni01@gmail.com>
To:     dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org,
        hpa@zytor.com, akpm@linux-foundation.org, rppt@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        zhiguangni01@gmail.com
Subject: [PATCH] mm/sparse:avoid null pointer access in memory_present()
Date:   Sat, 17 Jun 2023 14:40:36 +1000
Message-Id: <20230617044036.3985524-1-zhiguangni01@gmail.com>
Precedence: bulk

__nr_to_section() may return a null pointer,
before accessing the member variable section_mem_map,
we should first determine whether it is a null pointer.

Signed-off-by: Liam Ni <zhiguangni01@gmail.com>
---
 mm/sparse.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 4e6e3a9d49dc..37fa3818bc25 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -258,7 +258,7 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
 		set_section_nid(section, nid);
 
 		ms = __nr_to_section(section);
-		if (!ms->section_mem_map) {
+		if (ms && !ms->section_mem_map) {
 			ms->section_mem_map = sparse_encode_early_nid(nid) |
 							SECTION_IS_ONLINE;
 			__section_mark_present(ms, section);
-- 
2.25.1