From nobody Tue Oct 7 19:57:49 2025 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (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 8BA301F8BCB for ; Mon, 7 Jul 2025 11:04:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751886297; cv=none; b=qNFt4EDGXgq7Q+AbwNvfX9ag6+hyGeYjfW4i2tz3zt0lR2qUiLU0w6jxz2GwD64H/alBX0exVEjFfbV4gU0P5uzXEYIyGwapes1aYE5vGXOhb6bjqNDImKdZX6MBrpRZVwQ/t9rzOOIOSZMSJjbVZJIAr8mbBplpBjqzeSEAyV0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751886297; c=relaxed/simple; bh=9p8xTo8+z1wX9jIntt/DEWR+55R0l9UvlDWk3HYd5TI=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=F1kU5NCIynNIl74vJshaS4ljvRGOlndfsCiFH29yOJI9LvsHTclWkEes6JQ4J1HY/JFRvAiHqdx+0Q51ZCexsDIQtYdDbEQyFFqS1jxRnoPCZPi3qtkDrywUMH8vKlSy1oyHTtfQ7ENSKA+mVmy8fClIPaqMbONsZBMHaWrJ5yY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4bbLtp4FfNz2SSwY; Mon, 7 Jul 2025 19:02:58 +0800 (CST) Received: from kwepemg500010.china.huawei.com (unknown [7.202.181.71]) by mail.maildlp.com (Postfix) with ESMTPS id 6150B1A016C; Mon, 7 Jul 2025 19:04:51 +0800 (CST) Received: from huawei.com (10.67.174.76) by kwepemg500010.china.huawei.com (7.202.181.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 7 Jul 2025 19:04:50 +0800 From: Yuntao Liu To: , CC: , , , , , , , , Subject: [PATCH -next] mm/memory: fix null pointer dereference in fault_dirty_shared_page Date: Mon, 7 Jul 2025 10:51:18 +0000 Message-ID: <20250707105118.413056-1-liuyuntao12@huawei.com> 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: quoted-printable X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemg500010.china.huawei.com (7.202.181.71) Content-Type: text/plain; charset="utf-8" Page mapping with "VM_READ|VM_WRITE|VM_MAYREAD|VM_MAYWRITE|VM_SHARED", the first time accessing this address through a write operation will trigger a do_shared_fault, if mapping is anonymous, it can lead to a null pointer dereference. [ 23.232336][ T195] Call trace: [ 23.232542][ T195] file_update_time+0x2c/0xd8 [ 23.232801][ T195] fault_dirty_shared_page+0x1a0/0x220 [ 23.233099][ T195] do_shared_fault+0xe8/0x240 [ 23.233374][ T195] do_fault+0x78/0x240 [ 23.233629][ T195] handle_pte_fault+0x1f0/0x3f0 [ 23.233905][ T195] __handle_mm_fault+0x2b0/0x548 [ 23.234186][ T195] handle_mm_fault+0xd4/0x2f8 [ 23.234462][ T195] do_page_fault+0x2f0/0x5f8 [ 23.234727][ T195] do_translation_fault+0x8c/0xc8 [ 23.235021][ T195] do_mem_abort+0x68/0x100 [ 23.235283][ T195] el0_da+0x4c/0x1a8 [ 23.235551][ T195] el0t_64_sync_handler+0xe4/0x158 [ 23.235861][ T195] el0t_64_sync+0x37c/0x380 Signed-off-by: Yuntao Liu --- mm/memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index eaf98d518289..8106ef8a5036 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3412,7 +3412,7 @@ static vm_fault_t fault_dirty_shared_page(struct vm_f= ault *vmf) mapping =3D folio_raw_mapping(folio); folio_unlock(folio); =20 - if (!page_mkwrite) + if (!page_mkwrite && vma->vm_file) file_update_time(vma->vm_file); =20 /* --=20 2.34.1