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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 96F04C282C4 for ; Tue, 12 Feb 2019 21:48:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60F08222C0 for ; Tue, 12 Feb 2019 21:48:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="CzKb3LDc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732217AbfBLVsL (ORCPT ); Tue, 12 Feb 2019 16:48:11 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:39163 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727816AbfBLVsL (ORCPT ); Tue, 12 Feb 2019 16:48:11 -0500 Received: by mail-pl1-f196.google.com with SMTP id 101so96495pld.6 for ; Tue, 12 Feb 2019 13:48:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=3O1GoRWzdK7uBS+fqA4Rhukwloc4DD//vnltPS+KmL4=; b=CzKb3LDcgO0HzPC68h7u/21tqFWyuvHbakiKo0zM+l0seaFfFI6wUwFvh1h4clZ1i/ j02Gy2YboNf86tqljWRFTQ8cohZr7PFADjTP3kC6sEHvTb/uj4AN0azYwBSSocUN7ves 5uoAWu41agoG3LGFjHXHMHBrsyPsnOl8sC7to= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=3O1GoRWzdK7uBS+fqA4Rhukwloc4DD//vnltPS+KmL4=; b=qcAx8uZgrzZe2JuYakWUEvTsIBfefD8dmFDzrUrD5R+XuE+BloxO0V5yt7RlgdxhTE 8w5a2Tcw0Hw8Fs8S25fcV9FMGnhp2MS3M9c76WziWyhbYQ3REsgodfTrL8DHJxz7LCQJ galvzoAn3F4JGZwpueo+RbSfvupLJ5yMT+J242zFATb3PsN7WM8JydzZQFDMa2LkOi7g 4NXaH3iRqIn0FuKu0XXYAQ4v5L8RhbTGm26JK1H9OyCeg3DN46AMH1JMcnCONAsKddc9 U709Djj03JUcBMa7wKpbGhWhYOa1dUDLEfmlwpoY3TZgnv9zSrsIjVB6ZZXOU8CYK/FG 15qg== X-Gm-Message-State: AHQUAubL3F2m6Aa1+KTtK4B2xCOmGOHbYcrSAwzE1UK6IJEcs96RZ40u gbjtyZtJ4bTqXalpT7vHnxwrzKwa28I= X-Google-Smtp-Source: AHgI3IZtXjmY7KWbuyC+9olGituU+Iee0I42AXitGipRU7hWXw+d5G8s7ecFapbL0fr0KDsYHcmC5w== X-Received: by 2002:a17:902:8c81:: with SMTP id t1mr6245143plo.107.1550008090737; Tue, 12 Feb 2019 13:48:10 -0800 (PST) Received: from www.outflux.net (173-164-112-133-Oregon.hfc.comcastbusiness.net. [173.164.112.133]) by smtp.gmail.com with ESMTPSA id i8sm36900700pfj.18.2019.02.12.13.48.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Feb 2019 13:48:09 -0800 (PST) Date: Tue, 12 Feb 2019 13:48:08 -0800 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Yue Hu , Anton Vorontsov , Colin Cross , Tony Luck Subject: [PATCH] pstore/ram: Avoid needless alloc during header write Message-ID: <20190212214808.GA33512@beast> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since the header is a fixed small maximum size, just use a stack variable to avoid memory allocation in the write path. Signed-off-by: Kees Cook --- fs/pstore/ram.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index ec0e1da0596a..c5c685589e36 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -345,19 +345,15 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record) static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz, struct pstore_record *record) { - char *hdr; + char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */ size_t len; - hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n", + len = scnprintf(hdr, sizeof(hdr), + RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n", (time64_t)record->time.tv_sec, record->time.tv_nsec / 1000, record->compressed ? 'C' : 'D'); - if (WARN_ON_ONCE(!hdr)) - return 0; - - len = strlen(hdr); persistent_ram_write(prz, hdr, len); - kfree(hdr); return len; } -- 2.17.1 -- Kees Cook