Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933608AbaJVXVy (ORCPT ); Wed, 22 Oct 2014 19:21:54 -0400 Received: from mail-qg0-f44.google.com ([209.85.192.44]:36302 "EHLO mail-qg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933590AbaJVXVv (ORCPT ); Wed, 22 Oct 2014 19:21:51 -0400 MIME-Version: 1.0 In-Reply-To: <20141022165530.GA30358@redhat.com> References: <1413932228-27642-1-git-send-email-victor.kamensky@linaro.org> <1413932228-27642-2-git-send-email-victor.kamensky@linaro.org> <20141022165530.GA30358@redhat.com> Date: Wed, 22 Oct 2014 16:21:49 -0700 Message-ID: Subject: Re: [RFC PATCH] coredump: fix incomplete core file created when dump_skip was used last From: Victor Kamensky To: Oleg Nesterov Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, Andrew Morton , Kees Cook , open list Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22 October 2014 09:55, Oleg Nesterov wrote: > On 10/21, Victor Kamensky wrote: >> >> +static int dump_write_last_byte(struct coredump_params *cprm) >> +{ >> + char lastbyte = 0; >> + struct file *file = cprm->file; >> + >> + if (file->f_op->llseek && file->f_op->llseek != no_llseek) { >> + if (dump_interrupted() || >> + file->f_op->llseek(file, -1, SEEK_CUR) < 0) >> + return 0; >> + if (!dump_emit(cprm, &lastbyte, 1)) >> + return 0; >> + } >> + return 1; >> +} > > Perhaps do_truncate(cprm.file->f_path.dentry, ->f_pos) makes more sense? > > and unless I missed something cprm->last_op_status can be avoided, we can > simply check f_pos != i_size_read() at the end? Oleg, nice advise! Thanks. So the whole fix becomes something like this: diff --git a/fs/coredump.c b/fs/coredump.c index a93f7e6..8c17f1d 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -664,6 +664,14 @@ void do_coredump(const siginfo_t *siginfo) if (!dump_interrupted()) { file_start_write(cprm.file); core_dumped = binfmt->core_dump(&cprm); + /* + * If last operation was dump_skip with llseek, we need to + * truncate file up to f_pos to match expected size. + */ + if (!ispipe && + (cprm.file->f_pos > i_size_read(file_inode(cprm.file)))) + do_truncate(cprm.file->f_path.dentry, + cprm.file->f_pos, 0, cprm.file); file_end_write(cprm.file); } if (ispipe && core_pipe_limit) May I use your name with Suggested-by tag? Thanks, Victor > Oleg. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/