From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751500Ab2IZXZF (ORCPT ); Wed, 26 Sep 2012 19:25:05 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56870 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868Ab2IZXZD (ORCPT ); Wed, 26 Sep 2012 19:25:03 -0400 Date: Wed, 26 Sep 2012 16:25:02 -0700 From: Andrew Morton To: Alan Cox Cc: linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 2/2] binfmt_elf: Uninitialized variable Message-Id: <20120926162502.3b31071d.akpm@linux-foundation.org> In-Reply-To: <20120919144446.16893.24530.stgit@localhost.localdomain> References: <20120919144410.16893.57933.stgit@localhost.localdomain> <20120919144446.16893.24530.stgit@localhost.localdomain> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Sep 2012 15:45:01 +0100 Alan Cox wrote: > load_elf_interp has interp_map_addr carefully described as > "uninitialized_var" and marked so as to avoid a warning. However > if you trace the code it is passed into load_elf_interp and then > this value is checked against NULL. > > As this return value isn't used this is actually safe but it freaks > various analysis tools that see un-initialized memory addresses > being read before their value is ever defined. > > Set it to NULL as a matter of programming good taste if nothing else > > Signed-off-by: Alan Cox > --- > > fs/binfmt_elf.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index bf6d82b..5fb4801 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -880,7 +880,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) > } > > if (elf_interpreter) { > - unsigned long uninitialized_var(interp_map_addr); > + unsigned long interp_map_addr = 0; > > elf_entry = load_elf_interp(&loc->interp_elf_ex, > interpreter, That looks right to me.