From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Brian Gerst <brgerst@gmail.com>,
David Laight <David.Laight@aculab.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [patch V2 2/2] x86/ldt: Prevent ldt inheritance on exec
Date: Sat, 9 Dec 2017 19:28:31 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1712091927320.2301@nanos> (raw)
In-Reply-To: <alpine.DEB.2.20.1712091922340.2301@nanos>
On Sat, 9 Dec 2017, Thomas Gleixner wrote:
> On Fri, 8 Dec 2017, Thomas Gleixner wrote:
> > +int ldt_dup_context(struct mm_struct *old_mm, struct mm_struct *mm)
> > {
> > struct ldt_struct *new_ldt;
> > - struct mm_struct *old_mm;
> > int retval = 0;
> >
> > - mutex_init(&mm->context.lock);
> > - old_mm = current->mm;
> > - if (!old_mm) {
> > - mm->context.ldt = NULL;
> > + if (!old_mm)
> > return 0;
> > - }
> >
> > mutex_lock(&old_mm->context.lock);
>
> Bah. That's broken. It now nests into old_mm->mmap_sem which is the reverse
> lock order than in ldt_write. Will fix.
Confused myself. mmap_sem is not taken in mainline ldt_write. It's just in
the stuff I'm working on.
Thanks,
tglx
next prev parent reply other threads:[~2017-12-09 18:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-08 22:32 [patch V2 0/2] x86/ldt: Prevent LDT inheritance on exec() Thomas Gleixner
2017-12-08 22:32 ` [patch V2 1/2] arch: Allow arch_dup_mmap() to fail Thomas Gleixner
2017-12-08 22:32 ` [patch V2 2/2] x86/ldt: Prevent ldt inheritance on exec Thomas Gleixner
2017-12-09 18:24 ` Thomas Gleixner
2017-12-09 18:28 ` Thomas Gleixner [this message]
2017-12-11 12:13 ` Peter Zijlstra
2017-12-12 17:00 ` Thomas Gleixner
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