linux-kernel - NMI between switch_mm and switch

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-next>] [day] [month] [year] [list]

Message-ID: <19054.33655.297932.261580@cargo.ozlabs.ibm.com>
Date:	Tue, 28 Jul 2009 14:49:59 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>
CC:	linux-kernel@...r.kernel.org
Subject: NMI between switch_mm and switch_to

Ben H. suggested there might be a problem if we get a PMU interrupt
and try to do a stack trace of userspace in the interval between when
we call switch_mm() from sched.c:context_switch() and when we call
switch_to().  If we get an NMI in that interval and do a stack trace
of userspace, we'll see the registers of the old task but when we peek
at user addresses we'll see the memory image for the new task, so the
stack trace we get will be completely bogus.

Is this in fact also a problem on x86, or is there some subtle reason
why it can't happen there?

Paul.
--
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/