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 C8D3FC43457 for ; Fri, 16 Oct 2020 02:49:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 42B6D2087D for ; Fri, 16 Oct 2020 02:49:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="iNxPEa8G" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42B6D2087D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CD32394006F; Thu, 15 Oct 2020 22:49:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C5A1394006D; Thu, 15 Oct 2020 22:49:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B231F94006F; Thu, 15 Oct 2020 22:49:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0079.hostedemail.com [216.40.44.79]) by kanga.kvack.org (Postfix) with ESMTP id 8372F94006D for ; Thu, 15 Oct 2020 22:49:41 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1E26D1EE6 for ; Fri, 16 Oct 2020 02:49:41 +0000 (UTC) X-FDA: 77376258162.30.page73_371210d27219 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id EB0E1180B3AA7 for ; Fri, 16 Oct 2020 02:49:40 +0000 (UTC) X-HE-Tag: page73_371210d27219 X-Filterd-Recvd-Size: 3039 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 02:49:40 +0000 (UTC) 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 1585C208C7; Fri, 16 Oct 2020 02:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816579; bh=QH3J1yTdWGVTZhRpQWrYWeY+CtuYpjMq5hwuWm6wRdM=; h=Date:From:To:Subject:In-Reply-To:From; b=iNxPEa8G43LkKzTZyFNb5RToTVbhd+Qw8qu05zRr0udytyhnxm4R3DN81lT63jLO+ tCaa0D1BsM7qaB7VPGd5XJJMJqy7I7aMIOkFI9m2th1JeFux98CtIQU3jkMfY1blcc Td+wqyFRWe7gS7+XpqGbbXRoMXunhH06uqSm6bjU= Date: Thu, 15 Oct 2020 19:49:38 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ebiederm@xmission.com, hch@lst.de, hughd@google.com, jannh@google.com, linux-mm@kvack.org, 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: <20201016024938.1zaQbvIF0%akpm@linux-foundation.org> In-Reply-To: <20201015192732.f448da14e9854c7cb7299956@linux-foundation.org> User-Agent: s-nail v14.8.16 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: 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); _