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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 9FA30C43457 for ; Fri, 16 Oct 2020 03:12:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4584120878 for ; Fri, 16 Oct 2020 03:12:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602817965; bh=QH3J1yTdWGVTZhRpQWrYWeY+CtuYpjMq5hwuWm6wRdM=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=uTf3NRscKeTg87ApEjrA44Uv/x1tQgZz3YKtASTlU6+jYYcKJ7hNy67RKTmVVz9Xl MoCqIOXOZwBnbU3YAmnQwSsYkGhA/kIKJxWrek5MRXPWy9l9MxgUzhkulPOKVkJmwz Zw4y1EdzTEq2huTxv1jLKBwvUj5JpbUHV9kB/Tk8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390134AbgJPDMp (ORCPT ); Thu, 15 Oct 2020 23:12:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:48684 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389908AbgJPDMo (ORCPT ); Thu, 15 Oct 2020 23:12:44 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E70D32078A; Fri, 16 Oct 2020 03:12:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602817964; bh=QH3J1yTdWGVTZhRpQWrYWeY+CtuYpjMq5hwuWm6wRdM=; h=Date:From:To:Subject:In-Reply-To:From; b=2GGGch2GwKmyPIiBRN1uWPRVVFGRKTDnY974I5AhRiQvBjqD1c0xbpCfXh0Lgpk0q LufRVJ4zGl/uI3T+hCO0JWJ3aEE2HYWZYoJt7y+sp+vc4xnkZg4UAXWE3Q0AwFnXbI c/Kuc7H6Ga8+JmX97eFKyt+znRhF1pWvYJ2h0o78= Date: Thu, 15 Oct 2020 20:12:43 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ebiederm@xmission.com, hch@lst.de, hughd@google.com, jannh@google.com, mm-commits@vger.kernel.org, oleg@redhat.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Subject: [patch 137/156] coredump: let dump_emit() bail out on short writes Message-ID: <20201016031243.daSAejNL7%akpm@linux-foundation.org> In-Reply-To: <20201015194043.84cda0c1d6ca2a6847f2384a@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Jann Horn Subject: coredump: let dump_emit() bail out on short writes 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. Link: http://lkml.kernel.org/r/20200827114932.3572699-3-jannh@google.com Signed-off-by: Jann Horn Suggested-by: Linus Torvalds Acked-by: Linus Torvalds Cc: Christoph Hellwig Cc: Alexander Viro Cc: "Eric W . Biederman" Cc: Oleg Nesterov Cc: Hugh Dickins Signed-off-by: Andrew Morton --- fs/coredump.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) --- a/fs/coredump.c~coredump-let-dump_emit-bail-out-on-short-writes +++ a/fs/coredump.c @@ -840,17 +840,17 @@ int dump_emit(struct coredump_params *cp 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); _