Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753193AbZGAMKA (ORCPT ); Wed, 1 Jul 2009 08:10:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752640AbZGAMJx (ORCPT ); Wed, 1 Jul 2009 08:09:53 -0400 Received: from mx2.redhat.com ([66.187.237.31]:37143 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752421AbZGAMJw (ORCPT ); Wed, 1 Jul 2009 08:09:52 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells Subject: [PATCH] FDPIC: Ignore the loader's PT_GNU_STACK when calculating the stack size To: vapier.adi@gmail.com, rgetz@blackfin.uclinux.org, lethal@linux-sh.org Cc: dhowells@redhat.com, gerg@uclinux.org, uclinux-dist-devel@blackfin.uclinux.org, linux-kernel@vger.kernel.org Date: Wed, 01 Jul 2009 13:08:14 +0100 Message-ID: <20090701120814.30741.10146.stgit@warthog.procyon.org.uk> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2207 Lines: 60 Ignore the loader's PT_GNU_STACK when calculating the stack size, and only consider the executable's PT_GNU_STACK, assuming the executable has one. Currently the behaviour is to take the largest stack size and use that, but that means you can't reduce the stack size in the executable. The loader's stack size should probably only be used when executing the loader directly. WARNING: This patch is slightly dangerous - it may render a system inoperable if the loader's stack size is larger than that of important executables, and the system relies unknowingly on this increasing the size of the stack. Signed-off-by: David Howells --- fs/binfmt_elf_fdpic.c | 19 +++++++++++-------- 1 files changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 81ca047..58c49fa 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -283,20 +283,23 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm, } stack_size = exec_params.stack_size; - if (stack_size < interp_params.stack_size) - stack_size = interp_params.stack_size; - if (exec_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) executable_stack = EXSTACK_ENABLE_X; else if (exec_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) executable_stack = EXSTACK_DISABLE_X; - else if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) - executable_stack = EXSTACK_ENABLE_X; - else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) - executable_stack = EXSTACK_DISABLE_X; - else + else executable_stack = EXSTACK_DEFAULT; + if (stack_size == 0) { + stack_size = interp_params.stack_size; + if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) + executable_stack = EXSTACK_ENABLE_X; + else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) + executable_stack = EXSTACK_DISABLE_X; + else + executable_stack = EXSTACK_DEFAULT; + } + retval = -ENOEXEC; if (stack_size == 0) goto error; -- 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/