From patchwork Fri Oct 16 02:49:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11840779 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 203A714B4 for ; Fri, 16 Oct 2020 02:49:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C4EB720E65 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 C4EB720E65 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) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C5A1394006D; Thu, 15 Oct 2020 22:49:41 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org 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-Original-To: linux-mm@kvack.org 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-Spam-Summary: 1,0,0,388817c03f2f3954,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:69:355:379:800:960:967:973:988:989:1260:1263:1345:1359:1381:1431:1437:1534:1541:1711:1730:1747:1777:1792:2393:2525:2559:2563:2682:2685:2859:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3352:3865:3867:3868:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4321:5007:6261:6653:7576:7903:7904:8599:9025:9545:10004:10913:11658:11914:12043:12048:12296:12297:12517:12519:12555:12679:12783:12986:13069:13311:13357:13846:14181:14384:14721:14849:21080:21451:21627:21939:21990:30054,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201;04yghzuzph4cus6k9hdkkhip8do5typk1pz6go3bi819upe88ot53anws588zdm.dnauqt7ru4jho45rtii3m3111pi3zqtetwskicaaj3yyksha176bbbg8s1s1ksf.w-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime :23,LUA_ 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);