All of lore.kernel.org
 help / color / mirror / Atom feed
From: Frantisek Hrbata <fhrbata@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
	oleg@redhat.com, kamaleshb@in.ibm.com, hechjie@cn.ibm.com,
	akpm@linux-foundation.org, dvlasenk@redhat.com,
	prarit@redhat.com, lwoodman@redhat.com, hannsj_uhl@de.ibm.com
Subject: Re: [PATCH 1/1] x86: add phys addr validity check for /dev/mem mmap
Date: Thu, 14 Aug 2014 19:53:46 +0200	[thread overview]
Message-ID: <20140814175346.GB7575@localhost.localdomain> (raw)
In-Reply-To: <53ECEFF5.1040800@zytor.com>

On Thu, Aug 14, 2014 at 10:20:53AM -0700, H. Peter Anvin wrote:
> On 08/14/2014 09:36 AM, Dave Hansen wrote:
> > Thanks for dredging this back up!
> > 
> > On 08/14/2014 07:18 AM, Frantisek Hrbata wrote:
> >> +int valid_phys_addr_range(phys_addr_t addr, size_t count)
> >> +{
> >> +	return addr + count <= __pa(high_memory);
> >> +}
> > 
> > Is this correct on 32-bit?  It would limit /dev/mem to memory below 896MB.
> > 
> 
> Last I checked, /dev/mem was already broken for highmem... which is
> actually a problem.  I would prefer to see it fixed.
> 
> 	-hpa
> 

Hi Peter,

thank you for jumping in again. I'm not going to pretent I fully understand this
code, as proven by Dave :), but wouldn't it help just to move the high_memory
check directly to the xlate_dev_mem_ptr. Meaning no high_memory check in
valid_phys_addr_range for x86. I sent more info in my reply to Dave's mail.

Again many thanks.


-- 
Frantisek Hrbata

WARNING: multiple messages have this Message-ID (diff)
From: Frantisek Hrbata <fhrbata@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
	oleg@redhat.com, kamaleshb@in.ibm.com, hechjie@cn.ibm.com,
	akpm@linux-foundation.org, dvlasenk@redhat.com,
	prarit@redhat.com, lwoodman@redhat.com, hannsj_uhl@de.ibm.com
Subject: Re: [PATCH 1/1] x86: add phys addr validity check for /dev/mem mmap
Date: Thu, 14 Aug 2014 19:53:46 +0200	[thread overview]
Message-ID: <20140814175346.GB7575@localhost.localdomain> (raw)
In-Reply-To: <53ECEFF5.1040800@zytor.com>

On Thu, Aug 14, 2014 at 10:20:53AM -0700, H. Peter Anvin wrote:
> On 08/14/2014 09:36 AM, Dave Hansen wrote:
> > Thanks for dredging this back up!
> > 
> > On 08/14/2014 07:18 AM, Frantisek Hrbata wrote:
> >> +int valid_phys_addr_range(phys_addr_t addr, size_t count)
> >> +{
> >> +	return addr + count <= __pa(high_memory);
> >> +}
> > 
> > Is this correct on 32-bit?  It would limit /dev/mem to memory below 896MB.
> > 
> 
> Last I checked, /dev/mem was already broken for highmem... which is
> actually a problem.  I would prefer to see it fixed.
> 
> 	-hpa
> 

Hi Peter,

thank you for jumping in again. I'm not going to pretent I fully understand this
code, as proven by Dave :), but wouldn't it help just to move the high_memory
check directly to the xlate_dev_mem_ptr. Meaning no high_memory check in
valid_phys_addr_range for x86. I sent more info in my reply to Dave's mail.

Again many thanks.


-- 
Frantisek Hrbata

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2014-08-14 17:54 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-14 14:18 [PATCH 0/1] Prevent possible PTE corruption with /dev/mem mmap Frantisek Hrbata
2014-08-14 14:18 ` Frantisek Hrbata
2014-08-14 14:18 ` [PATCH 1/1] x86: add phys addr validity check for " Frantisek Hrbata
2014-08-14 14:18   ` Frantisek Hrbata
2014-08-14 16:36   ` Dave Hansen
2014-08-14 16:36     ` Dave Hansen
2014-08-14 17:20     ` H. Peter Anvin
2014-08-14 17:20       ` H. Peter Anvin
2014-08-14 17:53       ` Frantisek Hrbata [this message]
2014-08-14 17:53         ` Frantisek Hrbata
2014-08-14 17:40     ` Frantisek Hrbata
2014-08-14 17:40       ` Frantisek Hrbata
2014-08-15 10:17   ` Frantisek Hrbata
2014-08-15 10:17     ` Frantisek Hrbata
2014-08-15 11:44 ` [PATCH V2 0/2] Prevent possible PTE corruption with " Frantisek Hrbata
2014-08-15 11:44   ` Frantisek Hrbata
2014-08-15 11:44   ` [PATCH V2 1/2] x86: add arch_pfn_possible helper Frantisek Hrbata
2014-08-15 11:44     ` Frantisek Hrbata
2014-08-15 11:44   ` [PATCH V2 2/2] x86: add phys addr validity check for /dev/mem mmap Frantisek Hrbata
2014-08-15 11:44     ` Frantisek Hrbata
2014-08-15 18:10     ` Dave Hansen
2014-08-15 18:10       ` Dave Hansen
2014-08-18 11:26       ` Frantisek Hrbata
2014-08-18 11:26         ` Frantisek Hrbata
2014-08-20 15:25   ` [PATCH 0/2] x86: allow read/write /dev/mem to access non-system RAM above high_memory Frantisek Hrbata
2014-08-20 15:25     ` Frantisek Hrbata
2014-08-20 15:25     ` [PATCH 1/2] x86: add high_memory check to (xlate|unxlate)_dev_mem_ptr Frantisek Hrbata
2014-08-20 15:25       ` Frantisek Hrbata
2014-08-20 15:25     ` [PATCH 2/2] x86: remove high_memory check from valid_phys_addr_range Frantisek Hrbata
2014-08-20 15:25       ` Frantisek Hrbata

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20140814175346.GB7575@localhost.localdomain \
    --to=fhrbata@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=dave.hansen@intel.com \
    --cc=dvlasenk@redhat.com \
    --cc=hannsj_uhl@de.ibm.com \
    --cc=hechjie@cn.ibm.com \
    --cc=hpa@zytor.com \
    --cc=kamaleshb@in.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=lwoodman@redhat.com \
    --cc=mingo@redhat.com \
    --cc=oleg@redhat.com \
    --cc=prarit@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.