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 43F49C4363A for ; Tue, 27 Oct 2020 00:13:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0297820754 for ; Tue, 27 Oct 2020 00:13:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603757620; bh=bMneyGtp3CeIJWhqmVnUJjLbZSLAA8NQVwKHREaNQk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=oKK5aEZEO6rqjmvSXLHKrKlopL7uvG3/DK4SAF1nbhQ6udGMa3TqZLA+T8//FkOL8 hDVs0dW7/2SL4l+IKaGigayYWrbc9izH3ldQu99dh/maYtJnsSizz9kGPMKiQyH6tj LYiXhMxG3zX+iIuNssb3PJqky091rBgCYuJT/WRM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439492AbgJ0ANi (ORCPT ); Mon, 26 Oct 2020 20:13:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:33640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2411793AbgJ0ALo (ORCPT ); Mon, 26 Oct 2020 20:11:44 -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 F2460216FD; Tue, 27 Oct 2020 00:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603757503; bh=bMneyGtp3CeIJWhqmVnUJjLbZSLAA8NQVwKHREaNQk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F0d62q8kqHicqTUFHuQzHgQcjL3c80Hf2f1sm0aqQRPglOIHv9PW30qtfalIpjSvx cfZfoc3K/ycvrFlZgFLlS611oohByeqChEmqFahrTu8fYKrjgnNGWeyliq8P4IYpRA fvh8UYwgwkKNbYJHuPJiqz7dKh9N8LfsyeN7hkIs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhao Heming , Song Liu , Sasha Levin Subject: [PATCH AUTOSEL 4.4 16/25] md/bitmap: md_bitmap_get_counter returns wrong blocks Date: Mon, 26 Oct 2020 20:11:14 -0400 Message-Id: <20201027001123.1027642-16-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201027001123.1027642-1-sashal@kernel.org> References: <20201027001123.1027642-1-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 391090c455cea..65281f168c6fb 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1332,7 +1332,7 @@ __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