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=-12.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 E3603C433E3 for ; Wed, 26 Aug 2020 15:16:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2DC72075E for ; Wed, 26 Aug 2020 15:16:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="kI/DmR2c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728149AbgHZPQJ (ORCPT ); Wed, 26 Aug 2020 11:16:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727768AbgHZPPm (ORCPT ); Wed, 26 Aug 2020 11:15:42 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E8ECC061756 for ; Wed, 26 Aug 2020 08:15:42 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id a14so3150230ybm.13 for ; Wed, 26 Aug 2020 08:15:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=nVHuYaY9UtfQ5ceDG+IOgNARKDklUVVN28+71pW1fmk=; b=kI/DmR2cv1d9OJFdhnImUqHSGWV1ZqxdGqYUbrFMzIZoLjyBZUGrKg8nscJM4NLWSq aoE+SNTNoDERTGQQ81Jv2cVwHVUyQF4rCSPCBrfHjuNwC0mrKkXcOif6H4GqJ3ObCD1W ehHwAGA7xggv+ecKbvq/e9V08q0y/RhTUILd/sit7XJxc7N/40Scp5dgnxPvQs6qrvIc 79svxj8OV2XyIQ/z/HVb3yBer3F95VUgY2wiLnnZkGmA8ejGcBjzRg0W57SvZTtUh/lg tHZ2FutPYjZ60wnBdq/W3QSQ7XEECKopv3MAPfeOlE+Y2386UV58ZZUOqTacbwL3yjIs jL8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=nVHuYaY9UtfQ5ceDG+IOgNARKDklUVVN28+71pW1fmk=; b=PzfbNOFLcP+4escUxn4Ft5XOSu4019BxTF8bal1IjmreJk53J3ebkYYMYax8FOnnlr wmiHBBf2efDTQH2aorTMFJsU6OmiKnHE0YLKWrcmA3+W8i8Ovlz8QcnRvkeMP3yedyU2 cGcNWfWbHwEED5W6XFEIyDwrN/3NGg19FrD7hk/Wtz+Wmf/PgmrRXqDE+bfJ2O6po6wJ 29R4sMGzaiQhR1/SKTwkgWTztZJotIC9rd5SuL4YYvFgrV8jSrsCC6Cuxq9ikme9MGWM TBJCVvy9t3PvTi5kav9hktPf3uVW7N2uxCJrrzoDRbiOpN/oF6F74UcfF8ICTLntZNdQ R8fA== X-Gm-Message-State: AOAM532zMoQHDKfH1e+DpREokRWnR3j7iNKbC4XJ5kWbNC9t8r9sjZIK M/HzBrjh+UnkzP5Fq3JYmQuAnvirBQ== X-Google-Smtp-Source: ABdhPJw/rcqGxzh/fmBX9LEz09Jq8CAXmzs2q38x7tBY1D1+LTR0sUBBqdFxw+NulLkgSDFNyvsboxvOcQ== X-Received: from jannh2.zrh.corp.google.com ([2a00:79e0:1b:201:1a60:24ff:fea6:bf44]) (user=jannh job=sendgmr) by 2002:a25:3cc3:: with SMTP id j186mr21293924yba.208.1598454941009; Wed, 26 Aug 2020 08:15:41 -0700 (PDT) Date: Wed, 26 Aug 2020 17:14:45 +0200 In-Reply-To: <20200826151448.3404695-1-jannh@google.com> Message-Id: <20200826151448.3404695-3-jannh@google.com> Mime-Version: 1.0 References: <20200826151448.3404695-1-jannh@google.com> X-Mailer: git-send-email 2.28.0.297.g1956fa8f8d-goog Subject: [PATCH v4 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); -- 2.28.0.297.g1956fa8f8d-goog