2021-04-24 01:00:32

by Tong Zhang

Subject: [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

the PCI bridge might be NULL, so we'd better check before use it

[ 1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt]
[ 1.875880] Call Trace:
[ 1.876013] cobalt_probe.cold+0x1be/0xc11 [cobalt]
[ 1.876683] pci_device_probe+0x10f/0x1c0

Signed-off-by: Tong Zhang <[email protected]>
---
drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
index 0695078ef812..5687ed4869ac 100644
--- a/drivers/media/pci/cobalt/cobalt-driver.c
+++ b/drivers/media/pci/cobalt/cobalt-driver.c
@@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
u32 capa;
u16 stat, ctrl;

+ if (!pci_bus_dev)
+ return;
if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev))
return;

@@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt)
struct pci_dev *pci_dev = cobalt->pci_dev->bus->self;
u32 link;

+ if (!pci_dev)
+ return 0;
if (!pci_is_pcie(pci_dev))
return 0;
pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link);
--
2.25.1

2021-05-05 09:21:00

by Hans Verkuil

Subject: Re: [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

On 24/04/2021 02:52, Tong Zhang wrote:
> the PCI bridge might be NULL, so we'd better check before use it
>
> [ 1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt]
> [ 1.875880] Call Trace:
> [ 1.876013] cobalt_probe.cold+0x1be/0xc11 [cobalt]
> [ 1.876683] pci_device_probe+0x10f/0x1c0

How did you test this? With some virtualized PCI bus or something? I'm not sure
how this can happen.

Regards,

Hans

>
> Signed-off-by: Tong Zhang <[email protected]>
> ---
> drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
> index 0695078ef812..5687ed4869ac 100644
> --- a/drivers/media/pci/cobalt/cobalt-driver.c
> +++ b/drivers/media/pci/cobalt/cobalt-driver.c
> @@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
> u32 capa;
> u16 stat, ctrl;
>
> + if (!pci_bus_dev)
> + return;
> if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev))
> return;
>
> @@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt)
> struct pci_dev *pci_dev = cobalt->pci_dev->bus->self;
> u32 link;
>
> + if (!pci_dev)
> + return 0;
> if (!pci_is_pcie(pci_dev))
> return 0;
> pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link);
>

2021-05-10 22:35:48

by Tong Zhang

Subject: Re: [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

On Wed, May 5, 2021 at 2:18 AM Hans Verkuil <[email protected]> wrote:
>
> On 24/04/2021 02:52, Tong Zhang wrote:
> > the PCI bridge might be NULL, so we'd better check before use it
> >
> > [ 1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt]
> > [ 1.875880] Call Trace:
> > [ 1.876013] cobalt_probe.cold+0x1be/0xc11 [cobalt]
> > [ 1.876683] pci_device_probe+0x10f/0x1c0
>
> How did you test this? With some virtualized PCI bus or something? I'm not sure
> how this can happen.
>
Hello Hans,
IMHO bus->self is pci bridge device and we can have a system
configuration that does not have such a bridge,
in this case, bus->self is NULL.
- Tong
> Regards,
>
> Hans
>
> >
> > Signed-off-by: Tong Zhang <[email protected]>
> > ---
> > drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
> > index 0695078ef812..5687ed4869ac 100644
> > --- a/drivers/media/pci/cobalt/cobalt-driver.c
> > +++ b/drivers/media/pci/cobalt/cobalt-driver.c
> > @@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
> > u32 capa;
> > u16 stat, ctrl;
> >
> > + if (!pci_bus_dev)
> > + return;
> > if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev))
> > return;
> >
> > @@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt)
> > struct pci_dev *pci_dev = cobalt->pci_dev->bus->self;
> > u32 link;
> >
> > + if (!pci_dev)
> > + return 0;
> > if (!pci_is_pcie(pci_dev))
> > return 0;
> > pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link);
> >
>

2021-05-26 13:36:21

by Hans Verkuil

Subject: Re: [PATCH] media: cobalt: fix null-ptr-deref when there is no PCI bridge

On 11/05/2021 00:32, Tong Zhang wrote:
> On Wed, May 5, 2021 at 2:18 AM Hans Verkuil <[email protected]> wrote:
>>
>> On 24/04/2021 02:52, Tong Zhang wrote:
>>> the PCI bridge might be NULL, so we'd better check before use it
>>>
>>> [ 1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt]
>>> [ 1.875880] Call Trace:
>>> [ 1.876013] cobalt_probe.cold+0x1be/0xc11 [cobalt]
>>> [ 1.876683] pci_device_probe+0x10f/0x1c0
>>
>> How did you test this? With some virtualized PCI bus or something? I'm not sure
>> how this can happen.
>>
> Hello Hans,
> IMHO bus->self is pci bridge device and we can have a system
> configuration that does not have such a bridge,
> in this case, bus->self is NULL.

That does not answer my question :-)

You show a backtrace in the commit message, how did you get that?

Regards,

Hans

> - Tong
>> Regards,
>>
>> Hans
>>
>>>
>>> Signed-off-by: Tong Zhang <[email protected]>
>>> ---
>>> drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
>>> index 0695078ef812..5687ed4869ac 100644
>>> --- a/drivers/media/pci/cobalt/cobalt-driver.c
>>> +++ b/drivers/media/pci/cobalt/cobalt-driver.c
>>> @@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt)
>>> u32 capa;
>>> u16 stat, ctrl;
>>>
>>> + if (!pci_bus_dev)
>>> + return;
>>> if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev))
>>> return;
>>>
>>> @@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt)
>>> struct pci_dev *pci_dev = cobalt->pci_dev->bus->self;
>>> u32 link;
>>>
>>> + if (!pci_dev)
>>> + return 0;
>>> if (!pci_is_pcie(pci_dev))
>>> return 0;
>>> pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link);
>>>
>>