* [PATCH] Usb: host - Fix possible NULL derefrence.
[not found] <CGME20170130050640epcas2p1f856bc12df5d1ee6b9e0c66cf9dd6339@epcas2p1.samsung.com>
@ 2017-01-30 5:06 ` Shailendra Verma
2017-01-30 6:45 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Shailendra Verma @ 2017-01-30 5:06 UTC (permalink / raw)
To: Mathias Nyman, Greg Kroah-Hartman, Stephen Warren,
Thierry Reding, Alexandre Courbot, linux-usb, linux-tegra,
linux-kernel, p.shailesh, ashish.kalra, Shailendra Verma,
Shailendra Verma
of_device_get_match_data could return NULL, and so can cause
a NULL pointer dereference later.
Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>
---
drivers/usb/host/xhci-tegra.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index a59fafb..890c778 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -903,6 +903,10 @@ static int tegra_xusb_probe(struct platform_device *pdev)
return -ENOMEM;
tegra->soc = of_device_get_match_data(&pdev->dev);
+ if (!tegra->soc) {
+ dev_err(&pdev->dev, "no device match found\n");
+ return -ENODEV;
+ }
mutex_init(&tegra->lock);
tegra->dev = &pdev->dev;
--
1.7.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] Usb: host - Fix possible NULL derefrence.
2017-01-30 5:06 ` [PATCH] Usb: host - Fix possible NULL derefrence Shailendra Verma
@ 2017-01-30 6:45 ` Greg Kroah-Hartman
2017-01-30 7:03 ` Thierry Reding
0 siblings, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-01-30 6:45 UTC (permalink / raw)
To: Shailendra Verma
Cc: Mathias Nyman, Stephen Warren, Thierry Reding, Alexandre Courbot,
linux-usb, linux-tegra, linux-kernel, p.shailesh, ashish.kalra,
Shailendra Verma
On Mon, Jan 30, 2017 at 10:36:29AM +0530, Shailendra Verma wrote:
> of_device_get_match_data could return NULL, and so can cause
> a NULL pointer dereference later.
>
> Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>
> ---
> drivers/usb/host/xhci-tegra.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index a59fafb..890c778 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -903,6 +903,10 @@ static int tegra_xusb_probe(struct platform_device *pdev)
> return -ENOMEM;
>
> tegra->soc = of_device_get_match_data(&pdev->dev);
> + if (!tegra->soc) {
How would the driver be loaded and the probe function called if this
returns NULL?
Is this ever possible?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Usb: host - Fix possible NULL derefrence.
2017-01-30 6:45 ` Greg Kroah-Hartman
@ 2017-01-30 7:03 ` Thierry Reding
2017-01-30 19:37 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Thierry Reding @ 2017-01-30 7:03 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Shailendra Verma, Mathias Nyman, Stephen Warren,
Alexandre Courbot, linux-usb, linux-tegra, linux-kernel,
p.shailesh, ashish.kalra, Shailendra Verma
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On Mon, Jan 30, 2017 at 07:45:21AM +0100, Greg Kroah-Hartman wrote:
> On Mon, Jan 30, 2017 at 10:36:29AM +0530, Shailendra Verma wrote:
> > of_device_get_match_data could return NULL, and so can cause
> > a NULL pointer dereference later.
> >
> > Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>
> > ---
> > drivers/usb/host/xhci-tegra.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> > index a59fafb..890c778 100644
> > --- a/drivers/usb/host/xhci-tegra.c
> > +++ b/drivers/usb/host/xhci-tegra.c
> > @@ -903,6 +903,10 @@ static int tegra_xusb_probe(struct platform_device *pdev)
> > return -ENOMEM;
> >
> > tegra->soc = of_device_get_match_data(&pdev->dev);
> > + if (!tegra->soc) {
>
> How would the driver be loaded and the probe function called if this
> returns NULL?
>
> Is this ever possible?
No, it isn't. I've been NAK'ing this kind of patch for a while now.
There are two variants of this patch going about:
1) checking the return value of of_match_device()
2) checking the return value of of_device_get_match_data()
The same may also apply to of_match_node(), but I haven't seen that used
very much lately.
For of_match_device() the problem could technically occur if used in non
OF setups, because the device could be instantiated by hand in board
setup code. Tegra has been OF-only for a couple of years now, so there
is no way this can happen today.
of_device_get_match_data() is somewhat more complicated because it could
still return NULL if the OF table entry had its .data field set to NULL.
However in all drivers that I know that would be considered a bug, so
might as well let things crash at this point to make it immediately
obvious.
I had once been tempted to write a checkpatch rule for this, but I'm not
sure it's as easy as just warning if there's a check, because there are
some legitimate cases, even if they're very rare.
Thierry
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Usb: host - Fix possible NULL derefrence.
2017-01-30 7:03 ` Thierry Reding
@ 2017-01-30 19:37 ` Greg Kroah-Hartman
0 siblings, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-01-30 19:37 UTC (permalink / raw)
To: Thierry Reding
Cc: Shailendra Verma, Mathias Nyman, Stephen Warren,
Alexandre Courbot, linux-usb, linux-tegra, linux-kernel,
p.shailesh, ashish.kalra, Shailendra Verma
On Mon, Jan 30, 2017 at 08:03:23AM +0100, Thierry Reding wrote:
> On Mon, Jan 30, 2017 at 07:45:21AM +0100, Greg Kroah-Hartman wrote:
> > On Mon, Jan 30, 2017 at 10:36:29AM +0530, Shailendra Verma wrote:
> > > of_device_get_match_data could return NULL, and so can cause
> > > a NULL pointer dereference later.
> > >
> > > Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>
> > > ---
> > > drivers/usb/host/xhci-tegra.c | 4 ++++
> > > 1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> > > index a59fafb..890c778 100644
> > > --- a/drivers/usb/host/xhci-tegra.c
> > > +++ b/drivers/usb/host/xhci-tegra.c
> > > @@ -903,6 +903,10 @@ static int tegra_xusb_probe(struct platform_device *pdev)
> > > return -ENOMEM;
> > >
> > > tegra->soc = of_device_get_match_data(&pdev->dev);
> > > + if (!tegra->soc) {
> >
> > How would the driver be loaded and the probe function called if this
> > returns NULL?
> >
> > Is this ever possible?
>
> No, it isn't. I've been NAK'ing this kind of patch for a while now.
> There are two variants of this patch going about:
>
> 1) checking the return value of of_match_device()
> 2) checking the return value of of_device_get_match_data()
>
> The same may also apply to of_match_node(), but I haven't seen that used
> very much lately.
>
> For of_match_device() the problem could technically occur if used in non
> OF setups, because the device could be instantiated by hand in board
> setup code. Tegra has been OF-only for a couple of years now, so there
> is no way this can happen today.
>
> of_device_get_match_data() is somewhat more complicated because it could
> still return NULL if the OF table entry had its .data field set to NULL.
> However in all drivers that I know that would be considered a bug, so
> might as well let things crash at this point to make it immediately
> obvious.
>
> I had once been tempted to write a checkpatch rule for this, but I'm not
> sure it's as easy as just warning if there's a check, because there are
> some legitimate cases, even if they're very rare.
Thanks for the info, patch is now dropped.
Shailendra, please be more careful.
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-01-30 5:06 ` [PATCH] Usb: host - Fix possible NULL derefrence Shailendra Verma
2017-01-30 6:45 ` Greg Kroah-Hartman
2017-01-30 7:03 ` Thierry Reding
2017-01-30 19:37 ` Greg Kroah-Hartman
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