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From: Ingo Molnar <mingo@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: mm: insure topdown mmap chooses addresses above security minimum
Date: Wed, 25 Sep 2013 17:44:36 +0000	[thread overview]
Message-ID: <20130925174436.GA14037@gmail.com> (raw)
In-Reply-To: <20130925171243.GA7428@tcpepper-desk.jf.intel.com>


* Timothy Pepper <timothy.c.pepper@linux.intel.com> wrote:

> On Wed 25 Sep at 09:30:49 +0200 mingo@kernel.org said:
> > >  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > >  	info.length = len;
> > > -	info.low_limit = PAGE_SIZE;
> > > +	info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > >  	info.high_limit = mm->mmap_base;
> > >  	info.align_mask = filp ? get_align_mask() : 0;
> > >  	info.align_offset = pgoff << PAGE_SHIFT;
> > 
> > There appears to be a lot of repetition in these methods - instead of 
> > changing 6 places it would be more future-proof to first factor out the 
> > common bits and then to apply the fix to the shared implementation.
> 
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
> 
> 	max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));

That redundancy would be automatically addressed by my suggestion.

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Timothy Pepper <timothy.c.pepper@linux.intel.com>
Cc: linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Russell King <linux@arm.linux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Ralf Baechle <ralf@linux-mips.org>,
	linux-mips@linux-mips.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	linuxppc-dev@lists.ozlabs.org, Paul Mundt <lethal@linux-sh.org>,
	linux-sh@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	sparclinux@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	James Morris <james.l.morris@oracle.com>,
	Michel Lespinasse <walken@google.com>,
	Rik van Riel <riel@redhat.com>
Subject: Re: mm: insure topdown mmap chooses addresses above security minimum
Date: Wed, 25 Sep 2013 19:44:36 +0200	[thread overview]
Message-ID: <20130925174436.GA14037@gmail.com> (raw)
In-Reply-To: <20130925171243.GA7428@tcpepper-desk.jf.intel.com>


* Timothy Pepper <timothy.c.pepper@linux.intel.com> wrote:

> On Wed 25 Sep at 09:30:49 +0200 mingo@kernel.org said:
> > >  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > >  	info.length = len;
> > > -	info.low_limit = PAGE_SIZE;
> > > +	info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > >  	info.high_limit = mm->mmap_base;
> > >  	info.align_mask = filp ? get_align_mask() : 0;
> > >  	info.align_offset = pgoff << PAGE_SHIFT;
> > 
> > There appears to be a lot of repetition in these methods - instead of 
> > changing 6 places it would be more future-proof to first factor out the 
> > common bits and then to apply the fix to the shared implementation.
> 
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
> 
> 	max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));

That redundancy would be automatically addressed by my suggestion.

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Timothy Pepper <timothy.c.pepper@linux.intel.com>
Cc: linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Russell King <linux@arm.linux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Ralf Baechle <ralf@linux-mips.org>,
	linux-mips@linux-mips.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	linuxppc-dev@lists.ozlabs.org, Paul Mundt <lethal@linux-sh.org>,
	linux-sh@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	sparclinux@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	James Morris <james.l.morris@oracle.com>,
	Michel Lespinasse <walken@google.com>,
	Rik van Riel <riel@redhat.com>
Subject: Re: mm: insure topdown mmap chooses addresses above security minimum
Date: Wed, 25 Sep 2013 19:44:36 +0200	[thread overview]
Message-ID: <20130925174436.GA14037@gmail.com> (raw)
In-Reply-To: <20130925171243.GA7428@tcpepper-desk.jf.intel.com>


* Timothy Pepper <timothy.c.pepper@linux.intel.com> wrote:

> On Wed 25 Sep at 09:30:49 +0200 mingo@kernel.org said:
> > >  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > >  	info.length = len;
> > > -	info.low_limit = PAGE_SIZE;
> > > +	info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > >  	info.high_limit = mm->mmap_base;
> > >  	info.align_mask = filp ? get_align_mask() : 0;
> > >  	info.align_offset = pgoff << PAGE_SHIFT;
> > 
> > There appears to be a lot of repetition in these methods - instead of 
> > changing 6 places it would be more future-proof to first factor out the 
> > common bits and then to apply the fix to the shared implementation.
> 
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
> 
> 	max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));

That redundancy would be automatically addressed by my suggestion.

Thanks,

	Ingo

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WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Timothy Pepper <timothy.c.pepper@linux.intel.com>
Cc: linux-mips@linux-mips.org, linux-sh@vger.kernel.org,
	linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	sparclinux@vger.kernel.org, Michel Lespinasse <walken@google.com>,
	Russell King <linux@arm.linux.org.uk>,
	x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
	Rik van Riel <riel@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
	James Morris <james.l.morris@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	linuxppc-dev@lists.ozlabs.org, Ralf Baechle <ralf@linux-mips.org>,
	Paul Mundt <lethal@linux-sh.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: mm: insure topdown mmap chooses addresses above security minimum
Date: Wed, 25 Sep 2013 19:44:36 +0200	[thread overview]
Message-ID: <20130925174436.GA14037@gmail.com> (raw)
In-Reply-To: <20130925171243.GA7428@tcpepper-desk.jf.intel.com>


* Timothy Pepper <timothy.c.pepper@linux.intel.com> wrote:

> On Wed 25 Sep at 09:30:49 +0200 mingo@kernel.org said:
> > >  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > >  	info.length = len;
> > > -	info.low_limit = PAGE_SIZE;
> > > +	info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > >  	info.high_limit = mm->mmap_base;
> > >  	info.align_mask = filp ? get_align_mask() : 0;
> > >  	info.align_offset = pgoff << PAGE_SHIFT;
> > 
> > There appears to be a lot of repetition in these methods - instead of 
> > changing 6 places it would be more future-proof to first factor out the 
> > common bits and then to apply the fix to the shared implementation.
> 
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
> 
> 	max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));

That redundancy would be automatically addressed by my suggestion.

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: mingo@kernel.org (Ingo Molnar)
To: linux-arm-kernel@lists.infradead.org
Subject: mm: insure topdown mmap chooses addresses above security minimum
Date: Wed, 25 Sep 2013 19:44:36 +0200	[thread overview]
Message-ID: <20130925174436.GA14037@gmail.com> (raw)
In-Reply-To: <20130925171243.GA7428@tcpepper-desk.jf.intel.com>


* Timothy Pepper <timothy.c.pepper@linux.intel.com> wrote:

> On Wed 25 Sep at 09:30:49 +0200 mingo at kernel.org said:
> > >  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > >  	info.length = len;
> > > -	info.low_limit = PAGE_SIZE;
> > > +	info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > >  	info.high_limit = mm->mmap_base;
> > >  	info.align_mask = filp ? get_align_mask() : 0;
> > >  	info.align_offset = pgoff << PAGE_SHIFT;
> > 
> > There appears to be a lot of repetition in these methods - instead of 
> > changing 6 places it would be more future-proof to first factor out the 
> > common bits and then to apply the fix to the shared implementation.
> 
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
> 
> 	max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));

That redundancy would be automatically addressed by my suggestion.

Thanks,

	Ingo

  reply	other threads:[~2013-09-25 17:44 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-24 21:23 mm: insure topdown mmap chooses addresses above security minimum Timothy Pepper
2013-09-24 21:23 ` Timothy Pepper
2013-09-24 21:23 ` Timothy Pepper
2013-09-24 21:23 ` Timothy Pepper
2013-09-24 21:23 ` Timothy Pepper
2013-09-24 21:23 ` Timothy Pepper
2013-09-24 21:28 ` Russell King - ARM Linux
2013-09-24 21:28   ` Russell King - ARM Linux
2013-09-24 21:28   ` Russell King - ARM Linux
2013-09-24 21:28   ` Russell King - ARM Linux
2013-09-24 21:28   ` Russell King - ARM Linux
2013-09-25  7:30 ` Ingo Molnar
2013-09-25  7:30   ` Ingo Molnar
2013-09-25  7:30   ` Ingo Molnar
2013-09-25  7:30   ` Ingo Molnar
2013-09-25  7:30   ` Ingo Molnar
2013-09-25 17:12   ` Timothy Pepper
2013-09-25 17:12     ` Timothy Pepper
2013-09-25 17:12     ` Timothy Pepper
2013-09-25 17:12     ` Timothy Pepper
2013-09-25 17:12     ` Timothy Pepper
2013-09-25 17:44     ` Ingo Molnar [this message]
2013-09-25 17:44       ` Ingo Molnar
2013-09-25 17:44       ` Ingo Molnar
2013-09-25 17:44       ` Ingo Molnar
2013-09-25 17:44       ` Ingo Molnar
2013-09-27 15:39       ` Timothy Pepper
2013-09-27 15:39         ` Timothy Pepper
2013-09-27 15:39         ` Timothy Pepper
2013-09-27 15:39         ` Timothy Pepper
2013-09-27 15:39         ` Timothy Pepper

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