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=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 272F2C433E4 for ; Tue, 18 Aug 2020 06:13:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0420C2075B for ; Tue, 18 Aug 2020 06:13:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="mJkEz75f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726656AbgHRGNA (ORCPT ); Tue, 18 Aug 2020 02:13:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbgHRGM5 (ORCPT ); Tue, 18 Aug 2020 02:12:57 -0400 Received: from mail-ed1-x54a.google.com (mail-ed1-x54a.google.com [IPv6:2a00:1450:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1872FC061343 for ; Mon, 17 Aug 2020 23:12:57 -0700 (PDT) Received: by mail-ed1-x54a.google.com with SMTP id c16so7468131edt.2 for ; Mon, 17 Aug 2020 23:12:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=GSVoeZY4VtJncRCsBDOJV6iGFCXNH029JG2AgbxMzIw=; b=mJkEz75fkVHT8du8gdQBjaw6pE2ldFlA4jAPMSL2QbrZWXnfCVbN0C+c08ERHBXu6g C2fnjAZnH5RpJUIy5bISJjpd5WjqtYLOVKzqSpZEUfB9oMJdSN28QzPbF9Nlo8946/Fj oMh5GZo83yuAfd3Li5R2BToVuUri/UWMuEmqmPuoHlnAFltI6gltdTVRb4pk9SMR8r3s VxGDiC/Qdhttg9SXgox69qIlULfK8Md8HEGzpeXVfTvQr/JMHA9T5dT2KQ+7AwF2YMXd KtyAFJ/QUHW796NNlto8dQliaZ6uR4Jj68ysPjJBEx1Nd/tzEky2FMVHrzXQJZ+L4CxF tGAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=GSVoeZY4VtJncRCsBDOJV6iGFCXNH029JG2AgbxMzIw=; b=WKVOgRq16YFY0SkdAt4KgSIzf4/ftWL/Ce8I/25BuCiR0wEF2jvDEcg9tPkDxzVItu dauNHSdZHyHZQYg2dFs4DbkLaFKs2MyeLs8mTmxtnIzwjpJ4gMEDkQiV42qa964d01Up MMhxFI+sxOBxcXAUu97pEdCFKAhdwSWnjdFp0gPcKP40utGjr3u8uIHuItbi1uHQ9Wtc sISSrIg+L61zSzPb6fgrtHsKAwN/a7GOPLSjBz/H/7GBodbaSMhAqVI4cNNuUPFmX1Zx ZOp3nZunMQrLnhyEs63qXUcgPNJNy1LuvA1cidJrQbtt59mca9JQYxL+IR7M2MKUKFNu M1Pw== X-Gm-Message-State: AOAM530twCiVTpKPNwXeBT9gQymPkXdA8WpOeISi5R9rt2sei0oP9GW4 UOkvmUh90E22Fsl15aad38qb3pb3UQ== X-Google-Smtp-Source: ABdhPJw8kbNtK89Z+bGnNpE12khmVpUyK5YNskcMYl1yh5qw2UP1aNNDhMVoCYncY9CyFubOVCb/FD841g== X-Received: by 2002:a50:d2c7:: with SMTP id q7mr17620488edg.61.1597731173685; Mon, 17 Aug 2020 23:12:53 -0700 (PDT) Date: Tue, 18 Aug 2020 08:12:36 +0200 In-Reply-To: <20200818061239.29091-1-jannh@google.com> Message-Id: <20200818061239.29091-3-jannh@google.com> Mime-Version: 1.0 References: <20200818061239.29091-1-jannh@google.com> X-Mailer: git-send-email 2.28.0.220.ged08abb693-goog Subject: [PATCH v3 2/5] coredump: Let dump_emit() bail out on short writes From: Jann Horn To: Andrew Morton Cc: Linus Torvalds , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Alexander Viro , "Eric W . Biederman" , Oleg Nesterov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org dump_emit() has a retry loop, but there seems to be no way for that retry logic to actually be used; and it was also buggy, writing the same data repeatedly after a short write. Let's just bail out on a short write. Suggested-by: Linus Torvalds Signed-off-by: Jann Horn --- fs/coredump.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 76e7c10edfc0..5e24c06092c9 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -840,17 +840,17 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr) ssize_t n; if (cprm->written + nr > cprm->limit) return 0; - while (nr) { - if (dump_interrupted()) - return 0; - n = __kernel_write(file, addr, nr, &pos); - if (n <= 0) - return 0; - file->f_pos = pos; - cprm->written += n; - cprm->pos += n; - nr -= n; - } + + + if (dump_interrupted()) + return 0; + n = __kernel_write(file, addr, nr, &pos); + if (n != nr) + return 0; + file->f_pos = pos; + cprm->written += n; + cprm->pos += n; + return 1; } EXPORT_SYMBOL(dump_emit); -- 2.28.0.220.ged08abb693-goog