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=unavailable 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 E161DC4363A for ; Tue, 27 Oct 2020 00:01:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9FBDD20773 for ; Tue, 27 Oct 2020 00:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603756894; bh=Iuz/2JXOYt0ENEVGezaeevDY+PL7lz1Y3OheSHKL4xo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ej+K1YIBmDf6D+Q8KBdKsz8/X3zsbwIqb+HjSeD2CQofauXwXLUZElNAeoK7KExCf gax+1G6W8HiFYPAJAGolenZ7IavMZW5+1xv0693jj3GVOgLWpRcCRPlo2xnGxetV8l eoj3g3pmbJPfM0L3v4YNFF2G9aNWjXFejYhPjukY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727402AbgJ0ABc (ORCPT ); Mon, 26 Oct 2020 20:01:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:35780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2411125AbgJZX4Z (ORCPT ); Mon, 26 Oct 2020 19:56:25 -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 46A0A221FC; Mon, 26 Oct 2020 23:56:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603756584; bh=Iuz/2JXOYt0ENEVGezaeevDY+PL7lz1Y3OheSHKL4xo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gnzWcCiLh+8pms//pHEFvyZA9oyOYkovSlgjj73ok1hXcJbYAvNO2JjdMadl0u1EA pXea2lxh8HbZWhTp4Zm/6oTu+slc8UarMrTxq0tJhcUySwryfT17FsjFeXYlXWUL5h kUjboPWX7lm7tocKRTmogi+slqGBtFmoXfyVIngY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhao Heming , Song Liu , Sasha Levin , linux-raid@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 57/80] md/bitmap: md_bitmap_get_counter returns wrong blocks Date: Mon, 26 Oct 2020 19:54:53 -0400 Message-Id: <20201026235516.1025100-57-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201026235516.1025100-1-sashal@kernel.org> References: <20201026235516.1025100-1-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/md-bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index 3ad18246fcb3c..3b6fb1664dbea 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -1372,7 +1372,7 @@ __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