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* [V2 PATCH] usb: mtu3: fix NULL pointer dereference
@ 2020-06-30  7:42 Chunfeng Yun
  2020-06-30 10:47 ` [PATCH v2] usb: mtu3: Fix NULL pointer dereferences Markus Elfring
  2020-07-01 11:58 ` [V2 PATCH] usb: mtu3: fix NULL pointer dereference Greg Kroah-Hartman
  0 siblings, 2 replies; 4+ messages in thread
From: Chunfeng Yun @ 2020-06-30  7:42 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Felipe Balbi
  Cc: linux-usb, linux-kernel, Chunfeng Yun, linux-mediatek,
	Matthias Brugger, Markus Elfring, linux-arm-kernel

Some pointers are dereferenced before successful checks.

Reported-by: Markus Elfring <Markus.Elfring@web.de>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
v2: nothing changed, but abandon another patch
---
 drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c
index f93732e..1689ca8 100644
--- a/drivers/usb/mtu3/mtu3_gadget.c
+++ b/drivers/usb/mtu3/mtu3_gadget.c
@@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep,
 
 static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
 {
-	struct mtu3_ep *mep = to_mtu3_ep(ep);
-	struct mtu3_request *mreq = to_mtu3_request(req);
+	struct mtu3_ep *mep;
+	struct mtu3_request *mreq;
 	struct mtu3_request *r;
+	struct mtu3 *mtu;
 	unsigned long flags;
 	int ret = 0;
-	struct mtu3 *mtu = mep->mtu;
 
-	if (!ep || !req || mreq->mep != mep)
+	if (!ep || !req)
+		return -EINVAL;
+
+	mep = to_mtu3_ep(ep);
+	mtu = mep->mtu;
+
+	mreq = to_mtu3_request(req);
+	if (mreq->mep != mep)
 		return -EINVAL;
 
 	dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req);
@@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
  */
 static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
 {
-	struct mtu3_ep *mep = to_mtu3_ep(ep);
-	struct mtu3 *mtu = mep->mtu;
+	struct mtu3_ep *mep;
+	struct mtu3 *mtu;
 	struct mtu3_request *mreq;
 	unsigned long flags;
 	int ret = 0;
@@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
 	if (!ep)
 		return -EINVAL;
 
+	mep = to_mtu3_ep(ep);
+	mtu = mep->mtu;
+
 	dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name);
 
 	spin_lock_irqsave(&mtu->lock, flags);
@@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
 /* Sets the halt feature with the clear requests ignored */
 static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep)
 {
-	struct mtu3_ep *mep = to_mtu3_ep(ep);
+	struct mtu3_ep *mep;
 
 	if (!ep)
 		return -EINVAL;
 
+	mep = to_mtu3_ep(ep);
 	mep->wedged = 1;
 
 	return usb_ep_set_halt(ep);
-- 
1.9.1
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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH v2] usb: mtu3: Fix NULL pointer dereferences
  2020-06-30  7:42 [V2 PATCH] usb: mtu3: fix NULL pointer dereference Chunfeng Yun
@ 2020-06-30 10:47 ` Markus Elfring
  2020-07-01 11:58 ` [V2 PATCH] usb: mtu3: fix NULL pointer dereference Greg Kroah-Hartman
  1 sibling, 0 replies; 4+ messages in thread
From: Markus Elfring @ 2020-06-30 10:47 UTC (permalink / raw)
  To: Chunfeng Yun, Greg Kroah-Hartman, Matthias Brugger, linux-usb,
	linux-arm-kernel, linux-mediatek
  Cc: Colin Ian King, kernel-janitors, linux-kernel

> Some pointers are dereferenced before successful checks.

I propose to reconsider and improve also this change description.

* Would a null pointer dereference be possible only with the variables “mep”
  and “mreq” in the implementation of the function “mtu3_gadget_dequeue”?
  (Can it make sense to split the patch according to this detail?)

* How do you think about to convert any more variable initialisations
  to later assignments?

* Will it become helpful to add the tag “Fixes” to the commit message?


…
> ---
> v2: nothing changed, but abandon another patch

Are there chances to take any previous patch review comments better into account
(besides the shown reduction of update steps)?


> ---
>  drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++-------

I suggest to replace the triple dashes before this diffstat by a blank line.

Regards,
Markus

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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [V2 PATCH] usb: mtu3: fix NULL pointer dereference
  2020-06-30  7:42 [V2 PATCH] usb: mtu3: fix NULL pointer dereference Chunfeng Yun
  2020-06-30 10:47 ` [PATCH v2] usb: mtu3: Fix NULL pointer dereferences Markus Elfring
@ 2020-07-01 11:58 ` Greg Kroah-Hartman
  2020-07-02  2:52   ` Chunfeng Yun
  1 sibling, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2020-07-01 11:58 UTC (permalink / raw)
  To: Chunfeng Yun
  Cc: Felipe Balbi, linux-usb, linux-kernel, linux-mediatek,
	Matthias Brugger, Markus Elfring, linux-arm-kernel

On Tue, Jun 30, 2020 at 03:42:22PM +0800, Chunfeng Yun wrote:
> Some pointers are dereferenced before successful checks.
> 
> Reported-by: Markus Elfring <Markus.Elfring@web.de>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
> v2: nothing changed, but abandon another patch
> ---
>  drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c
> index f93732e..1689ca8 100644
> --- a/drivers/usb/mtu3/mtu3_gadget.c
> +++ b/drivers/usb/mtu3/mtu3_gadget.c
> @@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep,
>  
>  static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
>  {
> -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> -	struct mtu3_request *mreq = to_mtu3_request(req);
> +	struct mtu3_ep *mep;
> +	struct mtu3_request *mreq;
>  	struct mtu3_request *r;
> +	struct mtu3 *mtu;
>  	unsigned long flags;
>  	int ret = 0;
> -	struct mtu3 *mtu = mep->mtu;
>  
> -	if (!ep || !req || mreq->mep != mep)
> +	if (!ep || !req)
> +		return -EINVAL;

How will either of those ever be NULL?  The kernel will not call this
function with either of them being NULL, right?

> +
> +	mep = to_mtu3_ep(ep);
> +	mtu = mep->mtu;
> +
> +	mreq = to_mtu3_request(req);
> +	if (mreq->mep != mep)
>  		return -EINVAL;
>  
>  	dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req);
> @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
>   */
>  static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
>  {
> -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> -	struct mtu3 *mtu = mep->mtu;
> +	struct mtu3_ep *mep;
> +	struct mtu3 *mtu;
>  	struct mtu3_request *mreq;
>  	unsigned long flags;
>  	int ret = 0;
> @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
>  	if (!ep)
>  		return -EINVAL;

Same here, how can that ever happen?

>  
> +	mep = to_mtu3_ep(ep);
> +	mtu = mep->mtu;
> +
>  	dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name);
>  
>  	spin_lock_irqsave(&mtu->lock, flags);
> @@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
>  /* Sets the halt feature with the clear requests ignored */
>  static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep)
>  {
> -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> +	struct mtu3_ep *mep;
>  
>  	if (!ep)
>  		return -EINVAL;

Again, same here.

thanks,

greg k-h

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http://lists.infradead.org/mailman/listinfo/linux-mediatek

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [V2 PATCH] usb: mtu3: fix NULL pointer dereference
  2020-07-01 11:58 ` [V2 PATCH] usb: mtu3: fix NULL pointer dereference Greg Kroah-Hartman
@ 2020-07-02  2:52   ` Chunfeng Yun
  0 siblings, 0 replies; 4+ messages in thread
From: Chunfeng Yun @ 2020-07-02  2:52 UTC (permalink / raw)
  To: Greg Kroah-Hartman
  Cc: Felipe Balbi, linux-usb, linux-kernel, linux-mediatek,
	Matthias Brugger, Markus Elfring, linux-arm-kernel

On Wed, 2020-07-01 at 13:58 +0200, Greg Kroah-Hartman wrote:
> On Tue, Jun 30, 2020 at 03:42:22PM +0800, Chunfeng Yun wrote:
> > Some pointers are dereferenced before successful checks.
> > 
> > Reported-by: Markus Elfring <Markus.Elfring@web.de>
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > ---
> > v2: nothing changed, but abandon another patch
> > ---
> >  drivers/usb/mtu3/mtu3_gadget.c | 25 ++++++++++++++++++-------
> >  1 file changed, 18 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c
> > index f93732e..1689ca8 100644
> > --- a/drivers/usb/mtu3/mtu3_gadget.c
> > +++ b/drivers/usb/mtu3/mtu3_gadget.c
> > @@ -332,14 +332,21 @@ static int mtu3_gadget_queue(struct usb_ep *ep,
> >  
> >  static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
> >  {
> > -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> > -	struct mtu3_request *mreq = to_mtu3_request(req);
> > +	struct mtu3_ep *mep;
> > +	struct mtu3_request *mreq;
> >  	struct mtu3_request *r;
> > +	struct mtu3 *mtu;
> >  	unsigned long flags;
> >  	int ret = 0;
> > -	struct mtu3 *mtu = mep->mtu;
> >  
> > -	if (!ep || !req || mreq->mep != mep)
> > +	if (!ep || !req)
> > +		return -EINVAL;
> 
> How will either of those ever be NULL?  The kernel will not call this
> function with either of them being NULL, right?
Yes, I find all class drivers already ensure they are not NULL.

> 
> > +
> > +	mep = to_mtu3_ep(ep);
> > +	mtu = mep->mtu;
> > +
> > +	mreq = to_mtu3_request(req);
> > +	if (mreq->mep != mep)
> >  		return -EINVAL;
> >  
> >  	dev_dbg(mtu->dev, "%s : req=%p\n", __func__, req);
> > @@ -373,8 +380,8 @@ static int mtu3_gadget_dequeue(struct usb_ep *ep, struct usb_request *req)
> >   */
> >  static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
> >  {
> > -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> > -	struct mtu3 *mtu = mep->mtu;
> > +	struct mtu3_ep *mep;
> > +	struct mtu3 *mtu;
> >  	struct mtu3_request *mreq;
> >  	unsigned long flags;
> >  	int ret = 0;
> > @@ -382,6 +389,9 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
> >  	if (!ep)
> >  		return -EINVAL;
> 
> Same here, how can that ever happen?
Maybe when the class driver has something wrong:)

You mean it's better to remove these unnecessary checks?

Thanks

> 
> >  
> > +	mep = to_mtu3_ep(ep);
> > +	mtu = mep->mtu;
> > +
> >  	dev_dbg(mtu->dev, "%s : %s...", __func__, ep->name);
> >  
> >  	spin_lock_irqsave(&mtu->lock, flags);
> > @@ -422,11 +432,12 @@ static int mtu3_gadget_ep_set_halt(struct usb_ep *ep, int value)
> >  /* Sets the halt feature with the clear requests ignored */
> >  static int mtu3_gadget_ep_set_wedge(struct usb_ep *ep)
> >  {
> > -	struct mtu3_ep *mep = to_mtu3_ep(ep);
> > +	struct mtu3_ep *mep;
> >  
> >  	if (!ep)
> >  		return -EINVAL;
> 
> Again, same here.
> 
> thanks,
> 
> greg k-h

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^ permalink raw reply	[flat|nested] 4+ messages in thread

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Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-30  7:42 [V2 PATCH] usb: mtu3: fix NULL pointer dereference Chunfeng Yun
2020-06-30 10:47 ` [PATCH v2] usb: mtu3: Fix NULL pointer dereferences Markus Elfring
2020-07-01 11:58 ` [V2 PATCH] usb: mtu3: fix NULL pointer dereference Greg Kroah-Hartman
2020-07-02  2:52   ` Chunfeng Yun

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