From patchwork Wed Apr 29 21:49:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jann Horn X-Patchwork-Id: 11518565 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 25D3315E6 for ; Wed, 29 Apr 2020 21:50:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F5842137B for ; Wed, 29 Apr 2020 21:50:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aiXVr9LW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727842AbgD2VuU (ORCPT ); Wed, 29 Apr 2020 17:50:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727828AbgD2VuS (ORCPT ); Wed, 29 Apr 2020 17:50:18 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18425C035494 for ; Wed, 29 Apr 2020 14:50:17 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id m20so4143532qvy.13 for ; Wed, 29 Apr 2020 14:50:17 -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=JqiR2vOdqFfBqjhyMGJp8d/qL3dB8+X/PfK7MWBosOQ=; b=aiXVr9LW0+RfYp/BGKCZwf2eFb8u9bW41qbryYBrMOTMAxizbTvkyUsj2hMqoewXVA EbenkI3pjlj6j3Jz6v58GVbjLsRucPnyBIwyrf/cQxI7QYwEK5k1uOps+KFUBQSyYzSq 4ScWZwqWRdd/I9EOQCike+A/g8LgBL08ZkugaoTqx2zKcpO0yY7MZeP+Y4VZXfi2opO+ u0ixT5IVpYsz33tv0SuE/w161GkFjCv2PC0mWH6RqlvaBsCA3Nae7CGPq+IMF6tcDpg/ xDEfx6+SvCzPkM2Gw22E+XqkcpxanCcgz9Szd+JSjxTdcGi6OboSgHQ79epRcTxfLjBk yKJA== 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=JqiR2vOdqFfBqjhyMGJp8d/qL3dB8+X/PfK7MWBosOQ=; b=DIkwbOGIoTk7yeYDjlxPGCFtn/WTV+e0nmI1hphAbUANO/zKTjeLzPxClRWU2LamAC ubqqL7UOHPUpMP8gV9nWeetuPiiQQTRJylOEjQYRX2XT1FmgtCSimnwJ55vGhK/o9QsR mvNJdK/Bz1oZROPhldu9He4QuSvldsbrea2Xyo7wQFml23PPCWIckT1HGnSzdActRMuY cwKLL+8BFrycutWhGzJVUIWfIhyjhkKcYnwI3b9rSPlp9FBmEu18W1DG1M7uWOVU19Gp nEc3rEccaT6SwLj2aW5XGvMYMJd202Avha6F/n+cVc7wSp77FtVCO74UrSFoq0X5e74v CQfg== X-Gm-Message-State: AGi0PuZec+Z4qLNHpzsftVRv18Wvgkh5eiKe/f95z+Bs7hhzx2st7Tl5 iBqEHjN91AAFFAwkeKuZWS0wJSh9dg== X-Google-Smtp-Source: APiQypIhYRdYrJfvjviu8u64QDDNe2LAeKB+wfqrsyuISOkwKNnezPoPTQS28YSpGgdHWAPJujbNXC6IaA== X-Received: by 2002:ad4:49d3:: with SMTP id j19mr34024184qvy.78.1588197016281; Wed, 29 Apr 2020 14:50:16 -0700 (PDT) Date: Wed, 29 Apr 2020 23:49:51 +0200 In-Reply-To: <20200429214954.44866-1-jannh@google.com> Message-Id: <20200429214954.44866-3-jannh@google.com> Mime-Version: 1.0 References: <20200429214954.44866-1-jannh@google.com> X-Mailer: git-send-email 2.26.2.526.g744177e7f7-goog Subject: [PATCH v2 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 , Russell King , linux-arm-kernel@lists.infradead.org, Mark Salter , Aurelien Jacquiot , linux-c6x-dev@linux-c6x.org, Yoshinori Sato , Rich Felker , linux-sh@vger.kernel.org Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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 408418e6aa131..d6fcc36a7db1f 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -823,17 +823,17 @@ 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);