2015-11-09 07:59:34

by Shailendra Verma

Subject: [PATCH] arch:arm:mm:Correction in the boundary check for module end address.

From: Shailendra Verma <[email protected]>

The module end boundary check is not proper.The out of bound value
of module end can produce undesired results.

Signed-off-by: Shailendra Verma <[email protected]>
Reviewed-by: Ravikant Bijendra Sharma <[email protected]>
---
linux-4.3-rc6/arch/arm/mm/pageattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-4.3-rc6/arch/arm/mm/pageattr.c b/linux-4.3-rc6/arch/arm/mm/pageattr.c
index cf30daf..be7fe4b 100644
--- a/linux-4.3-rc6/arch/arm/mm/pageattr.c
+++ b/linux-4.3-rc6/arch/arm/mm/pageattr.c
@@ -52,7 +52,7 @@ static int change_memory_common(unsigned long addr, int numpages,
if (start < MODULES_VADDR || start >= MODULES_END)
return -EINVAL;

- if (end < MODULES_VADDR || start >= MODULES_END)
+ if (end < MODULES_VADDR || end >= MODULES_END)
return -EINVAL;

data.set_mask = set_mask;
--
1.7.9.5

2015-11-09 15:35:52

by Jungseung Lee

Subject: Re: [PATCH] arch:arm:mm:Correction in the boundary check for module end address.

Hi,

2015-11-09 16:57 GMT+09:00 Shailendra Verma <[email protected]>:
> From: Shailendra Verma <[email protected]>
>
> The module end boundary check is not proper.The out of bound value
> of module end can produce undesired results.
>
> Signed-off-by: Shailendra Verma <[email protected]>
> Reviewed-by: Ravikant Bijendra Sharma <[email protected]>
> ---
> linux-4.3-rc6/arch/arm/mm/pageattr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-4.3-rc6/arch/arm/mm/pageattr.c b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> index cf30daf..be7fe4b 100644
> --- a/linux-4.3-rc6/arch/arm/mm/pageattr.c
> +++ b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> @@ -52,7 +52,7 @@ static int change_memory_common(unsigned long addr, int numpages,
> if (start < MODULES_VADDR || start >= MODULES_END)
> return -EINVAL;
>
> - if (end < MODULES_VADDR || start >= MODULES_END)
> + if (end < MODULES_VADDR || end >= MODULES_END)
> return -EINVAL;
>
> data.set_mask = set_mask;
> --
> 1.7.9.5
>
Same patch with proper format is already submitted by Hillf.
https://lkml.org/lkml/2015/5/3/202

Best Regards,
Jungseung Lee

2015-11-09 16:02:53

by Russell King - ARM Linux

Subject: Re: [PATCH] arch:arm:mm:Correction in the boundary check for module end address.

On Tue, Nov 10, 2015 at 12:35:50AM +0900, Jungseung Lee wrote:
> Hi,
>
> 2015-11-09 16:57 GMT+09:00 Shailendra Verma <[email protected]>:
> > From: Shailendra Verma <[email protected]>
> >
> > The module end boundary check is not proper.The out of bound value
> > of module end can produce undesired results.
> >
> > Signed-off-by: Shailendra Verma <[email protected]>
> > Reviewed-by: Ravikant Bijendra Sharma <[email protected]>
> > ---
> > linux-4.3-rc6/arch/arm/mm/pageattr.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/linux-4.3-rc6/arch/arm/mm/pageattr.c b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > index cf30daf..be7fe4b 100644
> > --- a/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > +++ b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > @@ -52,7 +52,7 @@ static int change_memory_common(unsigned long addr, int numpages,
> > if (start < MODULES_VADDR || start >= MODULES_END)
> > return -EINVAL;
> >
> > - if (end < MODULES_VADDR || start >= MODULES_END)
> > + if (end < MODULES_VADDR || end >= MODULES_END)
> > return -EINVAL;
> >
> > data.set_mask = set_mask;
> > --
> > 1.7.9.5
> >
> Same patch with proper format is already submitted by Hillf.
> https://lkml.org/lkml/2015/5/3/202

What happened to that patch? It should at least have had a:

Fixes: f2ca09f381a5 ("ARM: 8311/1: Don't use is_module_addr in setting page attributes")

tag on it, and it needs to find its way into the patch system. As
no one has reported a crash (I don't think it's crash-causing, but is
merely a correctness issue) I don't see any reason to backport it to
stable trees.

Other changes are needed here as well - the original commit creating
this contains:

+ if (!IS_ALIGNED(addr, PAGE_SIZE)) {
+ start &= PAGE_MASK;
+ end = start + size;
+ WARN_ON_ONCE(1);
+ }

which is truely amazing. Fine, it may not be intended to work with
non-aligned addresses, but if we're going to round the start down,
then rounding the end down as well like that is also buggy.

unsigned long start = addr;
unsigned long size = PAGE_SIZE * numpages;
unsigned long end = start + size;

if (WARN_ON_ONCE(!IS_ALIGNED(addr, PAGE_SIZE)) {
start &= PAGE_MASK;
end = PAGE_ALIGN(end);
}

would be much better - this will round 'end' up, so we encompass the
entire requested region.

--
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

2015-11-10 02:51:21

by Hillf Danton

Subject: Re: [PATCH] arch:arm:mm:Correction in the boundary check for module end address.

> On Tue, Nov 10, 2015 at 12:35:50AM +0900, Jungseung Lee wrote:
> > Hi,
> >
> > 2015-11-09 16:57 GMT+09:00 Shailendra Verma <[email protected]>:
> > > From: Shailendra Verma <[email protected]>
> > >
> > > The module end boundary check is not proper.The out of bound value
> > > of module end can produce undesired results.
> > >
> > > Signed-off-by: Shailendra Verma <[email protected]>
> > > Reviewed-by: Ravikant Bijendra Sharma <[email protected]>
> > > ---
> > > linux-4.3-rc6/arch/arm/mm/pageattr.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/linux-4.3-rc6/arch/arm/mm/pageattr.c b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > > index cf30daf..be7fe4b 100644
> > > --- a/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > > +++ b/linux-4.3-rc6/arch/arm/mm/pageattr.c
> > > @@ -52,7 +52,7 @@ static int change_memory_common(unsigned long addr, int numpages,
> > > if (start < MODULES_VADDR || start >= MODULES_END)
> > > return -EINVAL;
> > >
> > > - if (end < MODULES_VADDR || start >= MODULES_END)
> > > + if (end < MODULES_VADDR || end >= MODULES_END)
> > > return -EINVAL;
> > >
> > > data.set_mask = set_mask;
> > > --
> > > 1.7.9.5
> > >
> > Same patch with proper format is already submitted by Hillf.
> > https://lkml.org/lkml/2015/5/3/202
>
> What happened to that patch? It should at least have had a:
>
> Fixes: f2ca09f381a5 ("ARM: 8311/1: Don't use is_module_addr in setting page attributes")
>
> tag on it, and it needs to find its way into the patch system. As
> no one has reported a crash (I don't think it's crash-causing, but is
> merely a correctness issue) I don't see any reason to backport it to
> stable trees.
>
> Other changes are needed here as well - the original commit creating
> this contains:
>
> + if (!IS_ALIGNED(addr, PAGE_SIZE)) {
> + start &= PAGE_MASK;
> + end = start + size;
> + WARN_ON_ONCE(1);
> + }
>
> which is truely amazing. Fine, it may not be intended to work with
> non-aligned addresses, but if we're going to round the start down,
> then rounding the end down as well like that is also buggy.
>
> unsigned long start = addr;
> unsigned long size = PAGE_SIZE * numpages;
> unsigned long end = start + size;
>
> if (WARN_ON_ONCE(!IS_ALIGNED(addr, PAGE_SIZE)) {
> start &= PAGE_MASK;
> end = PAGE_ALIGN(end);
> }
>
> would be much better - this will round 'end' up, so we encompass the
> entire requested region.
>
Would you please respin, Shailendra, with Russell's comments
addressed, and with
Reported-by: Hillf Danton <[email protected]> ?

thanks
Hillf