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Message-ID: <CAHk-=whks0iE1f=Ka0_vo2PYg774P7FA8Y30YrOdUBGRH-ch9A@mail.gmail.com>
Date: Wed, 1 Apr 2020 19:05:59 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Jann Horn <jannh@...gle.com>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>, Alan Stern <stern@...land.harvard.edu>,
Andrea Parri <parri.andrea@...il.com>, Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>, Boqun Feng <boqun.feng@...il.com>,
Nicholas Piggin <npiggin@...il.com>, David Howells <dhowells@...hat.com>,
Jade Alglave <j.alglave@....ac.uk>, Luc Maranget <luc.maranget@...ia.fr>,
"Paul E. McKenney" <paulmck@...nel.org>, Akira Yokosawa <akiyks@...il.com>,
Daniel Lustig <dlustig@...dia.com>, Adam Zabrocki <pi3@....com.pl>,
kernel list <linux-kernel@...r.kernel.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>, Oleg Nesterov <oleg@...hat.com>,
Andy Lutomirski <luto@...capital.net>, Bernd Edlinger <bernd.edlinger@...mail.de>,
Kees Cook <keescook@...omium.org>, Andrew Morton <akpm@...ux-foundation.org>,
stable <stable@...r.kernel.org>, Marco Elver <elver@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH] signal: Extend exec_id to 64bits
On Wed, Apr 1, 2020 at 6:36 PM Jann Horn <jannh@...gle.com> wrote:
>
> Since the read is already protected by the tasklist_lock, an
> alternative might be to let the execve path also take that lock to
> protect the sequence number update,
No.
tasklist_lock is aboue the hottest lock there is in all of the kernel.
We're not doing stupid things for theoretical issues.
Stop this crazy argument.
A comment - sure. 64-bit atomics or very expensive locks? Not a chance.
Linus
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