From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18BEDC2D0A3 for ; Tue, 27 Oct 2020 00:16:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7EFE20754 for ; Tue, 27 Oct 2020 00:16:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603757767; bh=t9rjh0Autx1Z/k9xuCrsF1Ug04g+BFXVZnxmkR+zTEk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CE8mFNf9ASofI7yAB9IeWL49Q6jwAHvMX5HwVdruNnvigPgYrFP5f+wqAJNRHeUhb yKT+2BPtM1N1rn8zDzaXXQtUJayedx25i45z2dMCokl2qXiK/D9jnk7sRylc0JxwlI THXRE1xOuWCFjtw+KfV/w8xjT3zlOBS+uC0ErzpQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440568AbgJ0AQG (ORCPT ); Mon, 26 Oct 2020 20:16:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:60696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395196AbgJ0ALJ (ORCPT ); Mon, 26 Oct 2020 20:11:09 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9471E20882; Tue, 27 Oct 2020 00:11:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603757469; bh=t9rjh0Autx1Z/k9xuCrsF1Ug04g+BFXVZnxmkR+zTEk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qIgJN9aCSe+kE9RngNeUQK/Er/TAy8fuj0AOAjdfVsit7WuUElF5L/zNuY9QKqBFe ZNq/ynNZDW+elDKFDWAO4lmqCBANGpSHjyNfE36K3Mg1U0IFitrb0ko4BYXMxJ74Rd 7pIc8sTl/CEOS87C2Edse6vtL5IXgmkw48X+LFDI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhao Heming , Song Liu , Sasha Levin Subject: [PATCH AUTOSEL 4.9 21/30] md/bitmap: md_bitmap_get_counter returns wrong blocks Date: Mon, 26 Oct 2020 20:10:35 -0400 Message-Id: <20201027001044.1027349-21-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201027001044.1027349-1-sashal@kernel.org> References: <20201027001044.1027349-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhao Heming [ Upstream commit d837f7277f56e70d82b3a4a037d744854e62f387 ] md_bitmap_get_counter() has code: ``` if (bitmap->bp[page].hijacked || bitmap->bp[page].map == NULL) csize = ((sector_t)1) << (bitmap->chunkshift + PAGE_COUNTER_SHIFT - 1); ``` The minus 1 is wrong, this branch should report 2048 bits of space. With "-1" action, this only report 1024 bit of space. This bug code returns wrong blocks, but it doesn't inflence bitmap logic: 1. Most callers focus this function return value (the counter of offset), not the parameter blocks. 2. The bug is only triggered when hijacked is true or map is NULL. the hijacked true condition is very rare. the "map == null" only true when array is creating or resizing. 3. Even the caller gets wrong blocks, current code makes caller just to call md_bitmap_get_counter() one more time. Signed-off-by: Zhao Heming Signed-off-by: Song Liu Signed-off-by: Sasha Levin --- drivers/md/bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 63bff4cc70984..863fe19e906e6 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1339,7 +1339,7 @@ __acquires(bitmap->lock) if (bitmap->bp[page].hijacked || bitmap->bp[page].map == NULL) csize = ((sector_t)1) << (bitmap->chunkshift + - PAGE_COUNTER_SHIFT - 1); + PAGE_COUNTER_SHIFT); else csize = ((sector_t)1) << bitmap->chunkshift; *blocks = csize - (offset & (csize - 1)); -- 2.25.1