linux-kernel - Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <18715.59672.641830.690773@harpo.it.uu.se>
Date:	Thu, 13 Nov 2008 09:45:12 +0100
From:	Mikael Pettersson <mikpe@...uu.se>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>,
	Mikael Pettersson <mikpe@...uu.se>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding

H. Peter Anvin writes:
 > Hiroshi Shimamoto wrote:
 > > H. Peter Anvin wrote:
 > >> Mikael Pettersson wrote:
 > >>> It does cause each signal delivery to leak 2 uninitialised
 > >>> kernel bytes to the end of retcode[], which seems unnecessary.
 > >> Not just unnecessary, it is a huge no-no for security.
 > > 
 > > Am I missing important thing?
 > > The frame->retcode is 8 bytes and packed structure with padding
 > > is 10 bytes each, and the code is copied to user stack 8 bytes only.
 > > 
 > > err |= __copy_to_user(frame->retcode, &code, 8);
 > > 
 > > I don't think the behavior is changed.
 > > 
 > 
 > Ah, nevermind, then.  Then it fine, obviously.

Agreed. I wonder how on earth those templates ended
up as 10 bytes large when retcode[] always has been
8 bytes.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/