Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756141AbdGCOV2 (ORCPT ); Mon, 3 Jul 2017 10:21:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36810 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932826AbdGCNox (ORCPT ); Mon, 3 Jul 2017 09:44:53 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Kleikamp , Alexander Viro , linux-fsdevel@vger.kernel.org, Sasha Levin Subject: [PATCH 4.9 121/172] coredump: Ensure proper size of sparse core files Date: Mon, 3 Jul 2017 15:35:01 +0200 Message-Id: <20170703133419.963463245@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133414.260777365@linuxfoundation.org> References: <20170703133414.260777365@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2562 Lines: 77 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Kleikamp [ Upstream commit 4d22c75d4c7b5c5f4bd31054f09103ee490878fd ] 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 Signed-off-by: Al Viro Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/binfmt_elf.c | 1 + fs/coredump.c | 18 ++++++++++++++++++ include/linux/coredump.h | 1 + 3 files changed, 20 insertions(+) --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -2296,6 +2296,7 @@ static int elf_core_dump(struct coredump goto end_coredump; } } + dump_truncate(cprm); if (!elf_core_write_extra_data(cprm)) goto end_coredump; --- a/fs/coredump.c +++ b/fs/coredump.c @@ -833,3 +833,21 @@ int dump_align(struct coredump_params *c 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); --- 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