[PATCH] resource: Fix integer overflow at reallocation

[PATCH] resource: Fix integer overflow at reallocation

[Takashi Iwai]

We've got a bug report indicating a kernel panic at booting on an
x86-32 system, and it turned out to be the invalid resource assigned
after reallocation.  __find_resource() first aligns the resource start
address and resets the end address with start+size-1 accordingly, then
checks whether it's contained.  Here the end address may overflow the
integer, although resource_contains() still returns true because the
function validates only start and end address.  So this ends up with
returning an invalid resource (start > end).

There was already an attempt to cover such a problem in the commit
47ea91b4052d ("Resource: fix wrong resource window calculation"), but
this case is an overseen one.

This patch adds the validity check of the newly calculated resource
for avoiding the integer overflow problem.

Bugzilla: http://bugzilla.opensuse.org/show_bug.cgi?id=1086739
Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
Reported-and-tested-by: Michael Henders <hendersm@shaw.ca>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

Bjorn, I send this to you since the bug hits during PCI init, although
the culprit is in generic resource management.

 kernel/resource.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index e270b5048988..2af6c03858b9 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old,
 			alloc.start = constraint->alignf(constraint->alignf_data, &avail,
 					size, constraint->align);
 			alloc.end = alloc.start + size - 1;
-			if (resource_contains(&avail, &alloc)) {
+			if (alloc.start <= alloc.end &&
+			    resource_contains(&avail, &alloc)) {
 				new->start = alloc.start;
 				new->end = alloc.end;
 				return 0;
-- 
2.16.2

Re: [PATCH] resource: Fix integer overflow at reallocation

[Ram Pai]

On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote:
> We've got a bug report indicating a kernel panic at booting on an
> x86-32 system, and it turned out to be the invalid resource assigned
> after reallocation.  __find_resource() first aligns the resource start
> address and resets the end address with start+size-1 accordingly, then
> checks whether it's contained.  Here the end address may overflow the
> integer, although resource_contains() still returns true because the
> function validates only start and end address.  So this ends up with
> returning an invalid resource (start > end).
> 
> There was already an attempt to cover such a problem in the commit
> 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> this case is an overseen one.
> 
> This patch adds the validity check of the newly calculated resource
> for avoiding the integer overflow problem.

Should we move this check "alloc.start <= alloc.end" into resource_contains()?
Doing so will catch all uses of such erroneous (overflowing) resources.

RP

> 
> Bugzilla: https://urldefense.proofpoint.com/v2/url?u=http-3A__bugzilla.opensuse.org_show-5Fbug.cgi-3Fid-3D1086739&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=FoiwlR-LTJ9_EBQsLYSCqXuWrGhU1lXycdvhbaK7wOk&s=clxOtFUIAMlPNwQJZTaKnmIta9pMtJ8XprmwVd-ylvo&e=
> Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
> Reported-and-tested-by: Michael Henders <hendersm@shaw.ca>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
> 
> Bjorn, I send this to you since the bug hits during PCI init, although
> the culprit is in generic resource management.
> 
>  kernel/resource.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/resource.c b/kernel/resource.c
> index e270b5048988..2af6c03858b9 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old,
>  			alloc.start = constraint->alignf(constraint->alignf_data, &avail,
>  					size, constraint->align);
>  			alloc.end = alloc.start + size - 1;
> -			if (resource_contains(&avail, &alloc)) {
> +			if (alloc.start <= alloc.end &&
> +			    resource_contains(&avail, &alloc)) {
>  				new->start = alloc.start;
>  				new->end = alloc.end;
>  				return 0;
> -- 
> 2.16.2

-- 
Ram Pai

Re: [PATCH] resource: Fix integer overflow at reallocation

[Takashi Iwai]

On Mon, 02 Apr 2018 21:09:03 +0200,
Ram Pai wrote:
> 
> On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote:
> > We've got a bug report indicating a kernel panic at booting on an
> > x86-32 system, and it turned out to be the invalid resource assigned
> > after reallocation.  __find_resource() first aligns the resource start
> > address and resets the end address with start+size-1 accordingly, then
> > checks whether it's contained.  Here the end address may overflow the
> > integer, although resource_contains() still returns true because the
> > function validates only start and end address.  So this ends up with
> > returning an invalid resource (start > end).
> > 
> > There was already an attempt to cover such a problem in the commit
> > 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> > this case is an overseen one.
> > 
> > This patch adds the validity check of the newly calculated resource
> > for avoiding the integer overflow problem.
> 
> Should we move this check "alloc.start <= alloc.end" into resource_contains()?
> Doing so will catch all uses of such erroneous (overflowing) resources.

I thought of it, too.  OTOH, it's rather a validity check and doesn't
belong to resource_contains() semantics.  If the function returns
false, you don't know whether it's an invalid resource or it's really
not contained.

We may return an error code, but I'm not sure whether such an API
change is needed.  Maybe not.


thanks,

Takashi


> 
> RP
> 
> > 
> > Bugzilla: https://urldefense.proofpoint.com/v2/url?u=http-3A__bugzilla.opensuse.org_show-5Fbug.cgi-3Fid-3D1086739&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=FoiwlR-LTJ9_EBQsLYSCqXuWrGhU1lXycdvhbaK7wOk&s=clxOtFUIAMlPNwQJZTaKnmIta9pMtJ8XprmwVd-ylvo&e=
> > Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
> > Reported-and-tested-by: Michael Henders <hendersm@shaw.ca>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> > 
> > Bjorn, I send this to you since the bug hits during PCI init, although
> > the culprit is in generic resource management.
> > 
> >  kernel/resource.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/resource.c b/kernel/resource.c
> > index e270b5048988..2af6c03858b9 100644
> > --- a/kernel/resource.c
> > +++ b/kernel/resource.c
> > @@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old,
> >  			alloc.start = constraint->alignf(constraint->alignf_data, &avail,
> >  					size, constraint->align);
> >  			alloc.end = alloc.start + size - 1;
> > -			if (resource_contains(&avail, &alloc)) {
> > +			if (alloc.start <= alloc.end &&
> > +			    resource_contains(&avail, &alloc)) {
> >  				new->start = alloc.start;
> >  				new->end = alloc.end;
> >  				return 0;
> > -- 
> > 2.16.2
> 
> -- 
> Ram Pai
> 

Re: [PATCH] resource: Fix integer overflow at reallocation

[Sasha Levin]

Hi Takashi Iwai.

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag.
fixing commit: 23c570a67448 resource: ability to resize an allocated resource.

The bot has also determined it's probably a bug fixing patch. (score: 99.2157)

The bot has tested the following trees: v4.15.15, v4.14.32, v4.9.92, v4.4.126, 

v4.15.15: Build OK!
v4.14.32: Build OK!
v4.9.92: Build OK!
v4.4.126: Build OK!

--
Thanks.
Sasha

Re: [PATCH] resource: Fix integer overflow at reallocation

[Takashi Iwai]

On Mon, 02 Apr 2018 22:35:04 +0200,
Takashi Iwai wrote:
> 
> On Mon, 02 Apr 2018 21:09:03 +0200,
> Ram Pai wrote:
> > 
> > On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote:
> > > We've got a bug report indicating a kernel panic at booting on an
> > > x86-32 system, and it turned out to be the invalid resource assigned
> > > after reallocation.  __find_resource() first aligns the resource start
> > > address and resets the end address with start+size-1 accordingly, then
> > > checks whether it's contained.  Here the end address may overflow the
> > > integer, although resource_contains() still returns true because the
> > > function validates only start and end address.  So this ends up with
> > > returning an invalid resource (start > end).
> > > 
> > > There was already an attempt to cover such a problem in the commit
> > > 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> > > this case is an overseen one.
> > > 
> > > This patch adds the validity check of the newly calculated resource
> > > for avoiding the integer overflow problem.
> > 
> > Should we move this check "alloc.start <= alloc.end" into resource_contains()?
> > Doing so will catch all uses of such erroneous (overflowing) resources.
> 
> I thought of it, too.  OTOH, it's rather a validity check and doesn't
> belong to resource_contains() semantics.  If the function returns
> false, you don't know whether it's an invalid resource or it's really
> not contained.
> 
> We may return an error code, but I'm not sure whether such an API
> change is needed.  Maybe not.

FWIW, below is the revised one to move the check into
resource_contains().

My concern is, however, that the resource validity check isn't a job
of resource_contains().  OTOH, this may avoid other similar cases, so
it might be worth.

In anyway, if there is no objection, and anyone else doesn't want to
take, I'll forward this to Andrew as a poor orphan kid.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH v2] resource: Fix integer overflow at reallocation

We've got a bug report indicating a kernel panic at booting on an
x86-32 system, and it turned out to be the invalid resource assigned
after reallocation.  __find_resource() first aligns the resource start
address and resets the end address with start+size-1 accordingly, then
checks whether it's contained.  Here the end address may overflow the
integer, although resource_contains() still returns true because the
function validates only start and end address.  So this ends up with
returning an invalid resource (start > end).

There was already an attempt to cover such a problem in the commit
47ea91b4052d ("Resource: fix wrong resource window calculation"), but
this case is an overseen one.

This patch adds the validity check in resource_contains() to see
whether the given resource has a valid range for avoiding the integer
overflow problem.

Bugzilla: http://bugzilla.opensuse.org/show_bug.cgi?id=1086739
Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
Reported-and-tested-by: Michael Henders <hendersm@shaw.ca>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 include/linux/ioport.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index da0ebaec25f0..466d7be046eb 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -212,6 +212,9 @@ static inline bool resource_contains(struct resource *r1, struct resource *r2)
 		return false;
 	if (r1->flags & IORESOURCE_UNSET || r2->flags & IORESOURCE_UNSET)
 		return false;
+	/* sanity check whether it's a valid resource range */
+	if (r2->end < r2->start)
+		return false;
 	return r1->start <= r2->start && r1->end >= r2->end;
 }
 
-- 
2.16.3

Re: [PATCH] resource: Fix integer overflow at reallocation

[Ram Pai]

On Thu, Apr 05, 2018 at 04:40:15PM +0200, Takashi Iwai wrote:
> On Mon, 02 Apr 2018 22:35:04 +0200,
> Takashi Iwai wrote:
> > 
> > On Mon, 02 Apr 2018 21:09:03 +0200,
> > Ram Pai wrote:
> > > 
> > > On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote:
> > > > We've got a bug report indicating a kernel panic at booting on an
> > > > x86-32 system, and it turned out to be the invalid resource assigned
> > > > after reallocation.  __find_resource() first aligns the resource start
> > > > address and resets the end address with start+size-1 accordingly, then
> > > > checks whether it's contained.  Here the end address may overflow the
> > > > integer, although resource_contains() still returns true because the
> > > > function validates only start and end address.  So this ends up with
> > > > returning an invalid resource (start > end).
> > > > 
> > > > There was already an attempt to cover such a problem in the commit
> > > > 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> > > > this case is an overseen one.
> > > > 
> > > > This patch adds the validity check of the newly calculated resource
> > > > for avoiding the integer overflow problem.
> > > 
> > > Should we move this check "alloc.start <= alloc.end" into resource_contains()?
> > > Doing so will catch all uses of such erroneous (overflowing) resources.
> > 
> > I thought of it, too.  OTOH, it's rather a validity check and doesn't
> > belong to resource_contains() semantics.  If the function returns
> > false, you don't know whether it's an invalid resource or it's really
> > not contained.
> > 
> > We may return an error code, but I'm not sure whether such an API
> > change is needed.  Maybe not.
> 
> FWIW, below is the revised one to move the check into
> resource_contains().
> 
> My concern is, however, that the resource validity check isn't a job
> of resource_contains().  OTOH, this may avoid other similar cases, so
> it might be worth.
> 
> In anyway, if there is no objection, and anyone else doesn't want to
> take, I'll forward this to Andrew as a poor orphan kid.

I will stand by you as a poor-orphan-buddy. :-) 

Reviewed-by: Ram Pai <linuxram@us.ibm.com>

RP

> 
> 
> thanks,
> 
> Takashi
> 
> -- 8< --
> From: Takashi Iwai <tiwai@suse.de>
> Subject: [PATCH v2] resource: Fix integer overflow at reallocation
> 
> We've got a bug report indicating a kernel panic at booting on an
> x86-32 system, and it turned out to be the invalid resource assigned
> after reallocation.  __find_resource() first aligns the resource start
> address and resets the end address with start+size-1 accordingly, then
> checks whether it's contained.  Here the end address may overflow the
> integer, although resource_contains() still returns true because the
> function validates only start and end address.  So this ends up with
> returning an invalid resource (start > end).
> 
> There was already an attempt to cover such a problem in the commit
> 47ea91b4052d ("Resource: fix wrong resource window calculation"), but
> this case is an overseen one.
> 
> This patch adds the validity check in resource_contains() to see
> whether the given resource has a valid range for avoiding the integer
> overflow problem.



> 
> Bugzilla: https://urldefense.proofpoint.com/v2/url?u=http-3A__bugzilla.opensuse.org_show-5Fbug.cgi-3Fid-3D1086739&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=NNkNAWFZc1XRu3rkv7Y2sepSCe8re2cvNZuCJt5dWFE&s=7i3g3ZVYsUceGVK_ZKkCJIABp4l0RD59NelK3GoD8mI&e=
> Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
> Reported-and-tested-by: Michael Henders <hendersm@shaw.ca>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>  include/linux/ioport.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index da0ebaec25f0..466d7be046eb 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -212,6 +212,9 @@ static inline bool resource_contains(struct resource *r1, struct resource *r2)
>  		return false;
>  	if (r1->flags & IORESOURCE_UNSET || r2->flags & IORESOURCE_UNSET)
>  		return false;
> +	/* sanity check whether it's a valid resource range */
> +	if (r2->end < r2->start)
> +		return false;
>  	return r1->start <= r2->start && r1->end >= r2->end;
>  }
>  
> -- 
> 2.16.3

-- 
Ram Pai