From nobody Wed Dec 17 08:52:14 2025 Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3992E9460 for ; Fri, 12 Jul 2024 03:26:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720754800; cv=none; b=oB7nUVq0jmVGG85IwQUQ9/tLFh8CIt5e9/UvEbKMxvroQrW7vlpyB+9PzhdIbL1KMgodyfaKZVWMD4rnC0DMTAtHFJp7++2zRbn5DKB1JgHLtAVsARZYxREXlLYIAQMPhE5Eb5ywDMaxY6haPyKnag8TSJ3wWJDjBPPqH3eDAs8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720754800; c=relaxed/simple; bh=KCKytG2y0HDEEkP5vWtAxl58cdEHGx4HE52l765u4Lc=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=XsOs0zxtyIF3si5H8WPTH+HhY3pr5IMCAca0ANgHE27u05eMNaXEX00h3KA4t+jD0gfar+fxrfQuxd8fIQypVHZ5EA62crp+qXIFMZpcxqgK4wQF/ocM9MNu29fOVyVly4ruM4tdvy0HU6Zmq5+vbItYRHORu1cTJQeu64oKtvg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Z++ak1Lq; arc=none smtp.client-ip=95.215.58.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Z++ak1Lq" X-Envelope-To: akpm@linux-foundation.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1720754794; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=VWeQNJq+zI55ma4p1FwSxutTu1uuDdgE89/qb0lCzRY=; b=Z++ak1LqH047WRiwSMRDmUltLuYrojjoNRsJR68z/X+XIMT0Yvpe/Ex3cWJpFhL5glP4UY KV9iUdiiJ8L+ezFVxE6ZmUDUASrEb4w2yy574oUeHeK0g1Rz0t+RgerY7oJCHwdFyFwLSX j/qforvln5vTK2ekIUWdd/Ur7BcTLCQ= X-Envelope-To: kent.overstreet@linux.dev X-Envelope-To: linux-mm@kvack.org X-Envelope-To: linux-kernel@vger.kernel.org X-Envelope-To: tangyouling@kylinos.cn X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Youling Tang To: Andrew Morton Cc: Kent Overstreet , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Youling Tang Subject: [PATCH] mm: list_lru: Fix NULL pointer dereference in list_lru_add() Date: Fri, 12 Jul 2024 11:25:54 +0800 Message-Id: <20240712032554.444823-1-youling.tang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Youling Tang Note that list_lru_from_memcg_idx() may return NULL, so it is necessary to error handle the return value to avoid triggering NULL pointer dereference BUG. The issue was triggered for discussion [1], Link [1]: https://lore.kernel.org/linux-bcachefs/84de6cb1-57bd-42f7-8029-42= 03820ef0b4@linux.dev/T/#m901bb26cdb1d9d4bacebf0d034f0a5a712cc93a6 Signed-off-by: Youling Tang --- mm/list_lru.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/list_lru.c b/mm/list_lru.c index 3fd64736bc45..ee7424c3879d 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -94,6 +94,9 @@ bool list_lru_add(struct list_lru *lru, struct list_head = *item, int nid, spin_lock(&nlru->lock); if (list_empty(item)) { l =3D list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg)); + if (!l) + goto out; + list_add_tail(item, &l->list); /* Set shrinker bit if the first element was added */ if (!l->nr_items++) @@ -102,6 +105,7 @@ bool list_lru_add(struct list_lru *lru, struct list_hea= d *item, int nid, spin_unlock(&nlru->lock); return true; } +out: spin_unlock(&nlru->lock); return false; } --=20 2.34.1