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From: Willy Tarreau <w@1wt.eu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>,
	Michal Hocko <mhocko@kernel.org>, Hugh Dickins <hughd@google.com>,
	Oleg Nesterov <oleg@redhat.com>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
	Rik van Riel <riel@redhat.com>,
	Larry Woodman <lwoodman@redhat.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Tony Luck <tony.luck@intel.com>,
	"James E.J. Bottomley" <jejb@parisc-linux.org>,
	Helge Diller <deller@gmx.de>,
	James Hogan <james.hogan@imgtec.com>,
	Laura Abbott <labbott@redhat.com>, Greg KH <greg@kroah.com>,
	"security@kernel.org" <security@kernel.org>,
	Qualys Security Advisory <qsa@qualys.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Ximin Luo <infinity0@debian.org>
Subject: Re: [PATCH] mm: larger stack guard gap, between vmas
Date: Wed, 5 Jul 2017 21:18:58 +0200	[thread overview]
Message-ID: <20170705191858.GF24459@1wt.eu> (raw)
In-Reply-To: <CA+55aFz1t2CHY5wpsd2K2Wi9DaY8S_+on4V+XU2cCkxmtBA3oA@mail.gmail.com>

On Wed, Jul 05, 2017 at 12:17:20PM -0700, Linus Torvalds wrote:
> On Wed, Jul 5, 2017 at 11:59 AM, Willy Tarreau <w@1wt.eu> wrote:
> >
> > Don't you think that the option of having a sysctl to relax the check
> > per task wouldn't be easier for distros and safer overall ? Ie, emit
> > a warning the first time the gap is hit instead of segfaulting, then
> > reduce it to something that used to work (4k or 64k, I don't remember)
> > and try again ?
> 
> It used to be just 4k.
> 
> .. and I think that might be a valid way to find these things, but
> would it be safer? It basically disables the new stack gap entirely
> apart from the warning.

But only if the sysctl is set. It can simply be recommended to set it
if any program fails. We've done this for many years with other ones
like min_mmap_addr or tcp_ecn.

Willy

  reply	other threads:[~2017-07-05 19:19 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <alpine.LSU.2.11.1706190355140.2626@eggly.anvils>
2017-06-22 12:30 ` [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings
2017-06-22 12:46   ` Willy Tarreau
2017-06-22 12:58     ` Ben Hutchings
2017-06-22 13:10       ` Willy Tarreau
2017-06-22 13:28         ` Willy Tarreau
2017-06-22 13:15       ` [vs-plain] " Levente Polyak
2017-06-22 13:59         ` Willy Tarreau
2017-06-22 14:14           ` Ben Hutchings
2017-06-22 14:34             ` Willy Tarreau
2017-06-23  3:10               ` Andy Lutomirski
2017-06-23  4:42                 ` Linus Torvalds
2017-06-22 21:23             ` Helge Deller
2017-06-23  4:35   ` Hugh Dickins
2017-06-24  9:11     ` Hugh Dickins
2017-06-24 18:29       ` Ben Hutchings
     [not found] ` <CA+55aFx6j4na3BVRC2aQuf-kNp1jzGahN8To_SFpNu+H=gopJA@mail.gmail.com>
     [not found]   ` <20170619142358.GA32654@1wt.eu>
     [not found]     ` <1498009101.2655.6.camel@decadent.org.uk>
     [not found]       ` <20170621092419.GA22051@dhcp22.suse.cz>
     [not found]         ` <1498042057.2655.8.camel@decadent.org.uk>
2017-07-03 23:55           ` Ben Hutchings
2017-07-04  0:05             ` Linus Torvalds
2017-07-04  8:41               ` Michal Hocko
2017-07-04  9:35                 ` Michal Hocko
2017-07-04  9:47                   ` Willy Tarreau
2017-07-04 10:42                     ` Michal Hocko
2017-07-04 11:36                       ` Ben Hutchings
2017-07-04 12:00                         ` Michal Hocko
2017-07-04 12:11                           ` Michal Hocko
2017-07-04 12:21                           ` Ben Hutchings
2017-07-04 12:33                             ` Michal Hocko
2017-07-04 14:19                               ` Ximin Luo
2017-07-04 14:48                                 ` Michal Hocko
2017-07-04 15:51                         ` Willy Tarreau
2017-07-04 17:22                           ` Michal Hocko
2017-07-04 18:37                             ` Linus Torvalds
2017-07-04 18:39                               ` Willy Tarreau
2017-07-04 18:47                                 ` Linus Torvalds
2017-07-04 19:03                                   ` Willy Tarreau
2017-07-04 16:18                         ` Linus Torvalds
2017-07-04 16:27                           ` John Haxby
2017-07-04 17:02                             ` Willy Tarreau
2017-07-05 12:26                           ` Ben Hutchings
2017-07-04 17:11                         ` Willy Tarreau
2017-07-05 12:25                           ` Ben Hutchings
2017-07-04 23:01                         ` Ben Hutchings
2017-07-04 23:31                           ` Linus Torvalds
2017-07-05  6:36                             ` Michal Hocko
2017-07-05  8:14                               ` Willy Tarreau
2017-07-05  8:24                                 ` Michal Hocko
2017-07-05  9:15                                   ` Willy Tarreau
2017-07-05 12:21                                 ` Ben Hutchings
2017-07-05 13:52                                   ` Willy Tarreau
2017-07-05 14:19                                   ` Michal Hocko
2017-07-05 16:06                                   ` Linus Torvalds
2017-07-06  7:34                               ` Michal Hocko
2017-07-05 12:19                             ` Ben Hutchings
2017-07-05 14:23                               ` Michal Hocko
2017-07-05 15:25                                 ` Ben Hutchings
2017-07-05 15:59                                   ` Michal Hocko
2017-07-05 16:58                                   ` Ben Hutchings
2017-07-05 17:05                                     ` Michal Hocko
2017-07-05 17:24                                       ` Ben Hutchings
2017-07-05 17:15                                     ` Linus Torvalds
2017-07-05 23:35                                       ` Ben Hutchings
2017-07-05 23:51                                         ` Linus Torvalds
2017-07-06  8:24                                           ` Willy Tarreau
2017-07-06 10:11                                             ` Willy Tarreau
2017-07-10  2:40                                     ` [lkp-robot] [mm] a99d848d3b: kernel_BUG_at_mm/mmap.c kernel test robot
2017-07-05 16:15                                 ` [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski
2017-07-05 16:20                                   ` Linus Torvalds
2017-07-05 17:23                                     ` Andy Lutomirski
2017-07-05 19:32                                       ` Ben Hutchings
2017-07-05 20:40                                         ` Willy Tarreau
2017-07-05 20:53                                         ` Andy Lutomirski
2017-07-05 23:50                                           ` Ben Hutchings
2017-07-06  0:23                                             ` Andy Lutomirski
2017-07-05 23:50                                       ` Kees Cook
2017-07-05 23:55                                         ` Linus Torvalds
2017-07-06  0:31                                           ` Andy Lutomirski
2017-07-06  0:47                                             ` Linus Torvalds
2017-07-06  0:19                                         ` Andy Lutomirski
2017-07-06  2:45                                           ` Kees Cook
2017-07-06  5:23                                           ` Willy Tarreau
2017-07-06  5:33                                 ` Kevin Easton
2017-07-05 16:17                               ` Linus Torvalds
2017-07-05 18:59                                 ` Willy Tarreau
2017-07-05 19:17                                   ` Linus Torvalds
2017-07-05 19:18                                     ` Willy Tarreau [this message]
2017-07-05 19:21                                       ` Linus Torvalds
2017-07-05  1:16                           ` [vs-plain] " kseifried
2017-07-05 14:11                             ` Solar Designer
2017-07-04 10:46                   ` Michal Hocko
2017-07-04 10:51                     ` Michal Hocko
2017-07-04  0:27             ` Andy Lutomirski
2017-07-04 12:26             ` [vs-plain] " John Haxby

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