diff mbox series

PCI: endpoint: Fix NULL pointer dereference for ->get_features()

Message ID 20200311102852.5207-1-shradha.t@samsung.com
State New, archived
Delegated to: Lorenzo Pieralisi
Headers show
Series PCI: endpoint: Fix NULL pointer dereference for ->get_features() | expand

Commit Message

Shradha Todi March 11, 2020, 10:28 a.m. UTC
get_features ops of pci_epc_ops may return NULL, causing NULL pointer
dereference in pci_epf_test_bind function. Let us add a check for
pci_epc_feature pointer in pci_epf_test_bind before we access it to
avoid any such NULL pointer dereference and return -ENOTSUPP in case
pci_epc_feature is not found.

Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Sriram Dash <sriram.dash@samsung.com>
Signed-off-by: Shradha Todi <shradha.t@samsung.com>
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

Comments

Sriram Dash March 19, 2020, 1:36 p.m. UTC | #1
> From: Shradha Todi <shradha.t@samsung.com>
> Subject: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
> >get_features()
> 
> get_features ops of pci_epc_ops may return NULL, causing NULL pointer
> dereference in pci_epf_test_bind function. Let us add a check for
> pci_epc_feature pointer in pci_epf_test_bind before we access it to avoid any
> such NULL pointer dereference and return -ENOTSUPP in case pci_epc_feature
> is not found.
> 
> Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
> Signed-off-by: Sriram Dash <sriram.dash@samsung.com>
> Signed-off-by: Shradha Todi <shradha.t@samsung.com>
> ---

Hi Kishon,

Any update on this?


>  drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> b/drivers/pci/endpoint/functions/pci-epf-test.c
> index c9121b1b9fa9..af4537a487bf 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf *epf)
>  		return -EINVAL;
> 
>  	epc_features = pci_epc_get_features(epc, epf->func_no);
> -	if (epc_features) {
> -		linkup_notifier = epc_features->linkup_notifier;
> -		msix_capable = epc_features->msix_capable;
> -		msi_capable = epc_features->msi_capable;
> -		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> -		pci_epf_configure_bar(epf, epc_features);
> +	if (!epc_features) {
> +		dev_err(dev, "epc_features not implemented\n");
> +		return -ENOTSUPP;
>  	}
> 
> +	linkup_notifier = epc_features->linkup_notifier;
> +	msix_capable = epc_features->msix_capable;
> +	msi_capable = epc_features->msi_capable;
> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> +	pci_epf_configure_bar(epf, epc_features);
> +
>  	epf_test->test_reg_bar = test_reg_bar;
>  	epf_test->epc_features = epc_features;
> 
> --
> 2.17.1
Kishon Vijay Abraham I March 20, 2020, 10:20 a.m. UTC | #2
Hi Sriram,

On 3/19/2020 7:06 PM, Sriram Dash wrote:
>> From: Shradha Todi <shradha.t@samsung.com>
>> Subject: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
>>> get_features()
>>
>> get_features ops of pci_epc_ops may return NULL, causing NULL pointer
>> dereference in pci_epf_test_bind function. Let us add a check for
>> pci_epc_feature pointer in pci_epf_test_bind before we access it to avoid any
>> such NULL pointer dereference and return -ENOTSUPP in case pci_epc_feature
>> is not found.
>>
>> Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
>> Signed-off-by: Sriram Dash <sriram.dash@samsung.com>
>> Signed-off-by: Shradha Todi <shradha.t@samsung.com>
>> ---
> 
> Hi Kishon,
> 
> Any update on this?

Don't we access epc_features only after checking if epc_features is not NULL in
pci_epf_test_bind() function? However we are accessing epc_features in multiple
other functions all over pci-epf-test.

So the patch itself is correct though the commit log has to be fixed. You
should also check if all the endpoint controller drivers existing currently
provides epc_features.

Thanks
Kishon
> 
> 
>>  drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
>>  1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
>> b/drivers/pci/endpoint/functions/pci-epf-test.c
>> index c9121b1b9fa9..af4537a487bf 100644
>> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
>> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
>> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf *epf)
>>  		return -EINVAL;
>>
>>  	epc_features = pci_epc_get_features(epc, epf->func_no);
>> -	if (epc_features) {
>> -		linkup_notifier = epc_features->linkup_notifier;
>> -		msix_capable = epc_features->msix_capable;
>> -		msi_capable = epc_features->msi_capable;
>> -		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
>> -		pci_epf_configure_bar(epf, epc_features);
>> +	if (!epc_features) {
>> +		dev_err(dev, "epc_features not implemented\n");
>> +		return -ENOTSUPP;
>>  	}
>>
>> +	linkup_notifier = epc_features->linkup_notifier;
>> +	msix_capable = epc_features->msix_capable;
>> +	msi_capable = epc_features->msi_capable;
>> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
>> +	pci_epf_configure_bar(epf, epc_features);
>> +
>>  	epf_test->test_reg_bar = test_reg_bar;
>>  	epf_test->epc_features = epc_features;
>>
>> --
>> 2.17.1
> 
>
Sriram Dash April 2, 2020, 2:31 p.m. UTC | #3
> From: Kishon Vijay Abraham I <kishon@ti.com>
> Subject: Re: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
> >get_features()
> 
> Hi Sriram,
> 
> On 3/19/2020 7:06 PM, Sriram Dash wrote:
> >> From: Shradha Todi <shradha.t@samsung.com>
> >> Subject: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
> >>> get_features()
> >>
> >> get_features ops of pci_epc_ops may return NULL, causing NULL pointer
> >> dereference in pci_epf_test_bind function. Let us add a check for
> >> pci_epc_feature pointer in pci_epf_test_bind before we access it to
> >> avoid any such NULL pointer dereference and return -ENOTSUPP in case
> >> pci_epc_feature is not found.
> >>
> >> Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
> >> Signed-off-by: Sriram Dash <sriram.dash@samsung.com>
> >> Signed-off-by: Shradha Todi <shradha.t@samsung.com>
> >> ---
> >
> > Hi Kishon,
> >
> > Any update on this?
> 
> Don't we access epc_features only after checking if epc_features is not NULL in
> pci_epf_test_bind() function? However we are accessing epc_features in
> multiple other functions all over pci-epf-test.

We access the epc_feature after checking the NULL condition in the bind function.
However, we do not stop if the epc_feature is NULL and proceed for allocation in the
pci_epf_test_alloc_space function, for example. During this allocation, we do not check
for NULL condition for epc_feature and hence, if any controller driver is not providing
the epc features, it will panic accessing epc_features.

> 
> So the patch itself is correct though the commit log has to be fixed. You should
> also check if all the endpoint controller drivers existing currently provides
> epc_features.

At the moment, there is no issue for existing controller drivers as I can see almost
all drivers are providing epc_features. But, this is not a mandatory feature and some
controller drivers may not have epc_features implemented, may be in the near future.
But because we are dealing with the configfs, the application need not bother about
the driver details underneath.

IMO, the code should be fixed regardless and should not cause panic in any case.

> 
> Thanks
> Kishon
> >
> >
> >>  drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
> >>  1 file changed, 9 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> >> b/drivers/pci/endpoint/functions/pci-epf-test.c
> >> index c9121b1b9fa9..af4537a487bf 100644
> >> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> >> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> >> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> >>  		return -EINVAL;
> >>
> >>  	epc_features = pci_epc_get_features(epc, epf->func_no);
> >> -	if (epc_features) {
> >> -		linkup_notifier = epc_features->linkup_notifier;
> >> -		msix_capable = epc_features->msix_capable;
> >> -		msi_capable = epc_features->msi_capable;
> >> -		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> >> -		pci_epf_configure_bar(epf, epc_features);
> >> +	if (!epc_features) {
> >> +		dev_err(dev, "epc_features not implemented\n");
> >> +		return -ENOTSUPP;
> >>  	}
> >>
> >> +	linkup_notifier = epc_features->linkup_notifier;
> >> +	msix_capable = epc_features->msix_capable;
> >> +	msi_capable = epc_features->msi_capable;
> >> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> >> +	pci_epf_configure_bar(epf, epc_features);
> >> +
> >>  	epf_test->test_reg_bar = test_reg_bar;
> >>  	epf_test->epc_features = epc_features;
> >>
> >> --
> >> 2.17.1
> >
> >
Lorenzo Pieralisi July 6, 2020, 11:17 a.m. UTC | #4
On Thu, Apr 02, 2020 at 08:01:59PM +0530, Sriram Dash wrote:

[...]

> > So the patch itself is correct though the commit log has to be fixed. You should
> > also check if all the endpoint controller drivers existing currently provides
> > epc_features.
> 
> At the moment, there is no issue for existing controller drivers as I
> can see almost all drivers are providing epc_features. But, this is
> not a mandatory feature and some controller drivers may not have
> epc_features implemented, may be in the near future.  But because we
> are dealing with the configfs, the application need not bother about
> the driver details underneath.
> 
> IMO, the code should be fixed regardless and should not cause panic in
> any case.

What's this patch status please ?

Thanks,
Lorenzo

> > Thanks
> > Kishon
> > >
> > >
> > >>  drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
> > >>  1 file changed, 9 insertions(+), 6 deletions(-)
> > >>
> > >> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> > >> b/drivers/pci/endpoint/functions/pci-epf-test.c
> > >> index c9121b1b9fa9..af4537a487bf 100644
> > >> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > >> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > >> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> > >>  		return -EINVAL;
> > >>
> > >>  	epc_features = pci_epc_get_features(epc, epf->func_no);
> > >> -	if (epc_features) {
> > >> -		linkup_notifier = epc_features->linkup_notifier;
> > >> -		msix_capable = epc_features->msix_capable;
> > >> -		msi_capable = epc_features->msi_capable;
> > >> -		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> > >> -		pci_epf_configure_bar(epf, epc_features);
> > >> +	if (!epc_features) {
> > >> +		dev_err(dev, "epc_features not implemented\n");
> > >> +		return -ENOTSUPP;
> > >>  	}
> > >>
> > >> +	linkup_notifier = epc_features->linkup_notifier;
> > >> +	msix_capable = epc_features->msix_capable;
> > >> +	msi_capable = epc_features->msi_capable;
> > >> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> > >> +	pci_epf_configure_bar(epf, epc_features);
> > >> +
> > >>  	epf_test->test_reg_bar = test_reg_bar;
> > >>  	epf_test->epc_features = epc_features;
> > >>
> > >> --
> > >> 2.17.1
> > >
> > >
>
Sriram Dash July 6, 2020, 1:17 p.m. UTC | #5
> From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Sent: 06 July 2020 16:47
> Subject: Re: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
> >get_features()
> 
> On Thu, Apr 02, 2020 at 08:01:59PM +0530, Sriram Dash wrote:
> 
> [...]
> 
> > > So the patch itself is correct though the commit log has to be
> > > fixed. You should also check if all the endpoint controller drivers
> > > existing currently provides epc_features.
> >
> > At the moment, there is no issue for existing controller drivers as I
> > can see almost all drivers are providing epc_features. But, this is
> > not a mandatory feature and some controller drivers may not have
> > epc_features implemented, may be in the near future.  But because we
> > are dealing with the configfs, the application need not bother about
> > the driver details underneath.
> >
> > IMO, the code should be fixed regardless and should not cause panic in
> > any case.
> 
> What's this patch status please ?
>

Its not in the mainline tree as of now. However, we feel its important for
the drivers not using epc_features.
 
> Thanks,
> Lorenzo
> 
> > > Thanks
> > > Kishon
> > > >
> > > >
> > > >>  drivers/pci/endpoint/functions/pci-epf-test.c | 15
> > > >> +++++++++------
> > > >>  1 file changed, 9 insertions(+), 6 deletions(-)
> > > >>
> > > >> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> index c9121b1b9fa9..af4537a487bf 100644
> > > >> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf
*epf)
> > > >>  		return -EINVAL;
> > > >>
> > > >>  	epc_features = pci_epc_get_features(epc, epf->func_no);
> > > >> -	if (epc_features) {
> > > >> -		linkup_notifier = epc_features->linkup_notifier;
> > > >> -		msix_capable = epc_features->msix_capable;
> > > >> -		msi_capable = epc_features->msi_capable;
> > > >> -		test_reg_bar =
pci_epc_get_first_free_bar(epc_features);
> > > >> -		pci_epf_configure_bar(epf, epc_features);
> > > >> +	if (!epc_features) {
> > > >> +		dev_err(dev, "epc_features not implemented\n");
> > > >> +		return -ENOTSUPP;
> > > >>  	}
> > > >>
> > > >> +	linkup_notifier = epc_features->linkup_notifier;
> > > >> +	msix_capable = epc_features->msix_capable;
> > > >> +	msi_capable = epc_features->msi_capable;
> > > >> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> > > >> +	pci_epf_configure_bar(epf, epc_features);
> > > >> +
> > > >>  	epf_test->test_reg_bar = test_reg_bar;
> > > >>  	epf_test->epc_features = epc_features;
> > > >>
> > > >> --
> > > >> 2.17.1
> > > >
> > > >
> >
diff mbox series

Patch

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index c9121b1b9fa9..af4537a487bf 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -510,14 +510,17 @@  static int pci_epf_test_bind(struct pci_epf *epf)
 		return -EINVAL;
 
 	epc_features = pci_epc_get_features(epc, epf->func_no);
-	if (epc_features) {
-		linkup_notifier = epc_features->linkup_notifier;
-		msix_capable = epc_features->msix_capable;
-		msi_capable = epc_features->msi_capable;
-		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
-		pci_epf_configure_bar(epf, epc_features);
+	if (!epc_features) {
+		dev_err(dev, "epc_features not implemented\n");
+		return -ENOTSUPP;
 	}
 
+	linkup_notifier = epc_features->linkup_notifier;
+	msix_capable = epc_features->msix_capable;
+	msi_capable = epc_features->msi_capable;
+	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
+	pci_epf_configure_bar(epf, epc_features);
+
 	epf_test->test_reg_bar = test_reg_bar;
 	epf_test->epc_features = epc_features;