From patchwork Wed Jan 11 19:25:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Kleikamp X-Patchwork-Id: 9511075 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 611626075C for ; Wed, 11 Jan 2017 19:25:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 572B62867D for ; Wed, 11 Jan 2017 19:25:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4A26D28681; Wed, 11 Jan 2017 19:25:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E2CFB2867D for ; Wed, 11 Jan 2017 19:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756724AbdAKTZF (ORCPT ); Wed, 11 Jan 2017 14:25:05 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:28161 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753606AbdAKTZE (ORCPT ); Wed, 11 Jan 2017 14:25:04 -0500 Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v0BJP21j002348 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 11 Jan 2017 19:25:02 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id v0BJP2hs014641 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 11 Jan 2017 19:25:02 GMT Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id v0BJP1Q7002333; Wed, 11 Jan 2017 19:25:01 GMT Received: from [192.168.1.74] (/99.156.91.244) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 11 Jan 2017 11:25:01 -0800 Subject: [PATCH RESEND] coredump: Ensure proper size of sparse core files To: Alexander Viro References: <20161208181151.28127-1-dave.kleikamp@oracle.com> Cc: sparclinux@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org From: Dave Kleikamp Message-ID: <32910821-8b16-1107-20de-b34d029b3e9a@oracle.com> Date: Wed, 11 Jan 2017 13:25:00 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20161208181151.28127-1-dave.kleikamp@oracle.com> X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If the last section of a core file ends with an unmapped or zero page, the size of the file does not correspond with the last dump_skip() call. gdb complains that the file is truncated and can be confusing to users. After all of the vma sections are written, make sure that the file size is no smaller than the current file position. This problem can be demonstrated with gdb's bigcore testcase on the sparc architecture. Signed-off-by: Dave Kleikamp Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/binfmt_elf.c | 1 + fs/coredump.c | 18 ++++++++++++++++++ include/linux/coredump.h | 1 + 3 files changed, 20 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 29a02daf08a9..422370293cfd 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -2298,6 +2298,7 @@ static int elf_core_dump(struct coredump_params *cprm) goto end_coredump; } } + dump_truncate(cprm); if (!elf_core_write_extra_data(cprm)) goto end_coredump; diff --git a/fs/coredump.c b/fs/coredump.c index e525b6017cdf..ae6b05629ca1 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -833,3 +833,21 @@ int dump_align(struct coredump_params *cprm, int align) return mod ? dump_skip(cprm, align - mod) : 1; } EXPORT_SYMBOL(dump_align); + +/* + * Ensures that file size is big enough to contain the current file + * postion. This prevents gdb from complaining about a truncated file + * if the last "write" to the file was dump_skip. + */ +void dump_truncate(struct coredump_params *cprm) +{ + struct file *file = cprm->file; + loff_t offset; + + if (file->f_op->llseek && file->f_op->llseek != no_llseek) { + offset = file->f_op->llseek(file, 0, SEEK_CUR); + if (i_size_read(file->f_mapping->host) < offset) + do_truncate(file->f_path.dentry, offset, 0, file); + } +} +EXPORT_SYMBOL(dump_truncate); diff --git a/include/linux/coredump.h b/include/linux/coredump.h index d016a121a8c4..28ffa94aed6b 100644 --- a/include/linux/coredump.h +++ b/include/linux/coredump.h @@ -14,6 +14,7 @@ struct coredump_params; extern int dump_skip(struct coredump_params *cprm, size_t nr); extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr); extern int dump_align(struct coredump_params *cprm, int align); +extern void dump_truncate(struct coredump_params *cprm); #ifdef CONFIG_COREDUMP extern void do_coredump(const siginfo_t *siginfo); #else