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=-17.4 required=3.0 tests=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=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 750CAC83000 for ; Wed, 29 Apr 2020 21:50:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2F2C620757 for ; Wed, 29 Apr 2020 21:50:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aiXVr9LW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F2C620757 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D1BBB8E0007; Wed, 29 Apr 2020 17:50:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CF2C28E0001; Wed, 29 Apr 2020 17:50:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B96718E0007; Wed, 29 Apr 2020 17:50:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0029.hostedemail.com [216.40.44.29]) by kanga.kvack.org (Postfix) with ESMTP id A2B658E0001 for ; Wed, 29 Apr 2020 17:50:17 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 555FF8248047 for ; Wed, 29 Apr 2020 21:50:17 +0000 (UTC) X-FDA: 76762236474.14.trade10_27884e80ef05 X-HE-Tag: trade10_27884e80ef05 X-Filterd-Recvd-Size: 4307 Received: from mail-qv1-f73.google.com (mail-qv1-f73.google.com [209.85.219.73]) by imf32.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Apr 2020 21:50:16 +0000 (UTC) Received: by mail-qv1-f73.google.com with SMTP id w9so4102882qvs.22 for ; Wed, 29 Apr 2020 14:50:16 -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=GQMkwDkl3Oiky/Z0OFFGwAgU9o2fqGeiIufxuErvM8wfUi5OubWzC0JLaJd9Oh0Q+r BMYmKeihDoQijnNxSYVpAA0mNay39cYxWp9XBj9nxgS7TRP8wLD1LTR+67gff9kcsodR L/k6v9JFIwF+feafq1KiRZwHn4nBgO0V4JgZQiOn5hhxJzd1AR6RmjCxyZDnewlO450z MggK9/u/vrkakZKnr1WPrr0iCcnLffiK0qwcUXo58B/ovsjvJaU3q35a7s09V0vwkY3h mvD5AMsnmjtTm919d/lhEYLrhBl2P9GTcvu6lhFkQbSJbVWOBQNSKuQ5CszPAtCvGvHA DKHg== X-Gm-Message-State: AGi0PuZuFJsVH1Tt8JCoNpk7d7wTKzEDio+hyxDj4PiscdKNxUYdIyur KqBouQLWRcz32MZH9sMe8jUZmD5Nqg== 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 Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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); -- 2.26.2.526.g744177e7f7-goog