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(static.159.107.27.37.clients.your-server.de. [37.27.107.159]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a15636b69dsm1107694e87.82.2026.03.12.11.40.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 11:40:54 -0700 (PDT) From: Josh Law X-Google-Original-From: Josh Law To: "Liam R . Howlett" , Andrew Morton Cc: Alice Ryhl , Andrew Ballance , Josh Law , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] lib/maple_tree: fix potential NULL dereference in mas_pop_node() Date: Thu, 12 Mar 2026 18:40:53 +0000 Message-Id: <20260312184054.23481-1-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit If kmem_cache_alloc_from_sheaf() returns NULL (possible under GFP_NOWAIT pressure), mas_pop_node() falls through to the out label and dereferences the NULL pointer in memset(ret, 0, sizeof(*ret)). Add a WARN_ON_ONCE NULL check after the sheaf allocation to bail out early, matching the existing pattern for the !mas->sheaf case above. Signed-off-by: Josh Law --- lib/maple_tree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 739918e859e5..87a2ba6468ca 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1063,6 +1063,8 @@ static __always_inline struct maple_node *mas_pop_node(struct ma_state *mas) return NULL; ret = kmem_cache_alloc_from_sheaf(maple_node_cache, GFP_NOWAIT, mas->sheaf); + if (WARN_ON_ONCE(!ret)) + return NULL; out: memset(ret, 0, sizeof(*ret)); -- 2.34.1