From: Jeff Dike <jdike@addtoit.com>
To: Blaisorblade <blaisorblade@yahoo.it>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] [PATCH] x86_64 32-bit ptrace mangles sixth system call argument
Date: Fri, 2 Feb 2007 15:12:30 -0500 [thread overview]
Message-ID: <20070202201230.GA8533@ccure.user-mode-linux.org> (raw)
In-Reply-To: <200702021848.40114.blaisorblade@yahoo.it>
On Fri, Feb 02, 2007 at 06:48:39PM +0100, Blaisorblade wrote:
> Is this a recent regression or did this always happen?
I haven't looked at the history of the code, but it has the look of
something that's been there a long time.
> Is this the bug diagnosed by Bodo Stroesser time ago, or only it looks
> similar? I recall vaguely that in that bug RCX was corrupted.
No, RCX corruption is different - that happens when a sysexit is done
from a system call where userspace wasn't prepared to save and restore
RCX. sigreturn is the best example.
> Above all, how can UML run in SKAS0 mode with this bug (if it can)?
The impact is limited by several things -
it must be a 32-bit UML on a 64-bit host
the system call must have 6 arguments - mmap and pselect are
the only 6-argument system calls that I can find quickly
the system call must be made through sysenter - int 0x80 is
fine
But, a 32-bit UML making mmap calls through sysenter indeed does not run
very well.
Jeff
--
Work email - jdike at linux dot intel dot com
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next prev parent reply other threads:[~2007-02-02 20:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-31 22:45 [uml-devel] [PATCH] x86_64 32-bit ptrace mangles sixth system call argument Jeff Dike
2007-02-02 17:48 ` Blaisorblade
2007-02-02 20:12 ` Jeff Dike [this message]
2007-03-05 23:03 ` Blaisorblade
2007-03-05 23:10 ` Jeff Dike
2007-03-05 23:26 ` Blaisorblade
2007-03-09 21:50 ` Blaisorblade
2007-03-12 10:42 ` [uml-devel] [PATCH] x86_64 32-bit ptrace mangles sixth systemcall argument Bodo Stroesser
2007-03-12 22:12 ` Blaisorblade
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