linux-kernel - Re: [RFC patch] vsprintf: Add %pav extension for print_vma

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

Date:	Wed, 27 May 2015 14:19:08 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Joe Perches <joe@...ches.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC patch] vsprintf: Add %pav extension for print_vma_addr

On Wed, 27 May 2015 14:09:31 -0700 Joe Perches <joe@...ches.com> wrote:

> > Problems when CONFIG_PREEMPT=n.
> > 
> > > +	down_read(&mm->mmap_sem);
> > > +	vma = find_vma(mm, ip);
> > > +	if (vma && vma->vm_file) {
> > > +		struct file *f = vma->vm_file;
> > > +		char *gfp_buf = (char *)__get_free_page(GFP_KERNEL);
> > 
> > We shouldn't assume we can use GFP_KERNEL here.  Even if the
> > preempt_count() worked, we might be in a context which requires
> > GFP_NOFS or GFP_NOIO.
> 
> This code is basically a copy of the existing print_vma_addr()
> so is that true for all the existing uses too?

Yeah, the current code is pretty junky.  But normally print_vma_addr()
should never be called so nobody noticed...

In e8bff74a Ingo did a fiddle to preempt_conditional_sti() which looks
like it will address the CONFIG_PREEMPT=n issue, but only on x86.
--
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/