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* [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present
@ 2019-11-06  2:36 
  2019-11-06  7:29 ` Hans Verkuil
  0 siblings, 1 reply; 4+ messages in thread
From:  @ 2019-11-06  2:36 UTC (permalink / raw)
  To: Mauro Carvalho Chehab, Hans Verkuil, linux-media,
	Linux Kernel Mailing List
  Cc: Mike Isely at pobox

In some device configurations there's no radio or radio support in the
driver.  That's OK, as the driver sets itself up accordingly.  However
on tear-down in these caes it's still trying to tear down radio
related context when there isn't anything there, leading to
dereferences through a null pointer and chaos follows.

How this bug survived unfixed for 11 years in the pvrusb2 driver is a
mystery to me.

Signed-off-by: Mike Isely <isely@pobox.com>
---
 drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
index aa4fbc3e88cc..339119f6cc23 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
@@ -909,8 +909,12 @@ static void pvr2_v4l2_internal_check(struct pvr2_channel *chp)
 	pvr2_v4l2_dev_disassociate_parent(vp->dev_video);
 	pvr2_v4l2_dev_disassociate_parent(vp->dev_radio);
 	if (!list_empty(&vp->dev_video->devbase.fh_list) ||
-	    !list_empty(&vp->dev_radio->devbase.fh_list))
+	    ((vp->dev_radio != NULL) &&
+	     !list_empty(&vp->dev_radio->devbase.fh_list))) {
+		pvr2_trace(PVR2_TRACE_STRUCT,
+			   "pvr2_v4l2 internal_check exit-empty id=%p", vp);
 		return;
+	}
 	pvr2_v4l2_destroy_no_lock(vp);
 }
 
@@ -946,7 +950,8 @@ static int pvr2_v4l2_release(struct file *file)
 	kfree(fhp);
 	if (vp->channel.mc_head->disconnect_flag &&
 	    list_empty(&vp->dev_video->devbase.fh_list) &&
-	    list_empty(&vp->dev_radio->devbase.fh_list)) {
+	    ((vp->dev_radio == NULL) ||
+	     list_empty(&vp->dev_radio->devbase.fh_list))) {
 		pvr2_v4l2_destroy_no_lock(vp);
 	}
 	return 0;
-- 
2.20.1

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present
  2019-11-06  2:36 [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present 
@ 2019-11-06  7:29 ` Hans Verkuil
  2019-11-06 11:12   ` Mike Isely
  0 siblings, 1 reply; 4+ messages in thread
From: Hans Verkuil @ 2019-11-06  7:29 UTC (permalink / raw)
  To: Mike Isely at pobox, Mauro Carvalho Chehab, linux-media,
	Linux Kernel Mailing List

Hi Mike,

For some reason your mailer didn't include a "From:" line, only a "Reply-To:"
line. This means that the patch authorship is not detected by patchwork and
git. Can you repost with a valid From: line in the email header?

Thanks!

	Hans

On 11/6/19 3:36 AM,  wrote:
> In some device configurations there's no radio or radio support in the
> driver.  That's OK, as the driver sets itself up accordingly.  However
> on tear-down in these caes it's still trying to tear down radio
> related context when there isn't anything there, leading to
> dereferences through a null pointer and chaos follows.
> 
> How this bug survived unfixed for 11 years in the pvrusb2 driver is a
> mystery to me.
> 
> Signed-off-by: Mike Isely <isely@pobox.com>
> ---
>  drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> index aa4fbc3e88cc..339119f6cc23 100644
> --- a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> +++ b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
> @@ -909,8 +909,12 @@ static void pvr2_v4l2_internal_check(struct pvr2_channel *chp)
>  	pvr2_v4l2_dev_disassociate_parent(vp->dev_video);
>  	pvr2_v4l2_dev_disassociate_parent(vp->dev_radio);
>  	if (!list_empty(&vp->dev_video->devbase.fh_list) ||
> -	    !list_empty(&vp->dev_radio->devbase.fh_list))
> +	    ((vp->dev_radio != NULL) &&
> +	     !list_empty(&vp->dev_radio->devbase.fh_list))) {
> +		pvr2_trace(PVR2_TRACE_STRUCT,
> +			   "pvr2_v4l2 internal_check exit-empty id=%p", vp);
>  		return;
> +	}
>  	pvr2_v4l2_destroy_no_lock(vp);
>  }
>  
> @@ -946,7 +950,8 @@ static int pvr2_v4l2_release(struct file *file)
>  	kfree(fhp);
>  	if (vp->channel.mc_head->disconnect_flag &&
>  	    list_empty(&vp->dev_video->devbase.fh_list) &&
> -	    list_empty(&vp->dev_radio->devbase.fh_list)) {
> +	    ((vp->dev_radio == NULL) ||
> +	     list_empty(&vp->dev_radio->devbase.fh_list))) {
>  		pvr2_v4l2_destroy_no_lock(vp);
>  	}
>  	return 0;
> 


^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present
  2019-11-06  7:29 ` Hans Verkuil
@ 2019-11-06 11:12   ` Mike Isely
  0 siblings, 0 replies; 4+ messages in thread
From: Mike Isely @ 2019-11-06 11:12 UTC (permalink / raw)
  To: Hans Verkuil
  Cc: Mauro Carvalho Chehab, linux-media, Linux Kernel Mailing List,
	Mike Isely


Thanks for spotting that.  I think I had eliminated the from header 
because I thought I was seeing a duplicate from header and didn't want 
to cause confusion.  That'll teach me.

It's been reposted.

  -Mike

On Wed, 6 Nov 2019, Hans Verkuil wrote:

> Hi Mike,
> 
> For some reason your mailer didn't include a "From:" line, only a "Reply-To:"
> line. This means that the patch authorship is not detected by patchwork and
> git. Can you repost with a valid From: line in the email header?
> 
> Thanks!
> 
> 	Hans
> 

[...]

-- 

Mike Isely
isely @ isely (dot) net
PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8

^ permalink raw reply	[flat|nested] 4+ messages in thread
* [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present
@ 2019-11-06 11:11 Mike Isely
  0 siblings, 0 replies; 4+ messages in thread
From: Mike Isely @ 2019-11-06 11:11 UTC (permalink / raw)
  To: Mauro Carvalho Chehab, Hans Verkuil, linux-media,
	Linux Kernel Mailing List
  Cc: Mike Isely at pobox

In some device configurations there's no radio or radio support in the
driver.  That's OK, as the driver sets itself up accordingly.  However
on tear-down in these caes it's still trying to tear down radio
related context when there isn't anything there, leading to
dereferences through a null pointer and chaos follows.

How this bug survived unfixed for 11 years in the pvrusb2 driver is a
mystery to me.

Signed-off-by: Mike Isely <isely@pobox.com>
---
 drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
index aa4fbc3e88cc..339119f6cc23 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-v4l2.c
@@ -909,8 +909,12 @@ static void pvr2_v4l2_internal_check(struct pvr2_channel *chp)
 	pvr2_v4l2_dev_disassociate_parent(vp->dev_video);
 	pvr2_v4l2_dev_disassociate_parent(vp->dev_radio);
 	if (!list_empty(&vp->dev_video->devbase.fh_list) ||
-	    !list_empty(&vp->dev_radio->devbase.fh_list))
+	    ((vp->dev_radio != NULL) &&
+	     !list_empty(&vp->dev_radio->devbase.fh_list))) {
+		pvr2_trace(PVR2_TRACE_STRUCT,
+			   "pvr2_v4l2 internal_check exit-empty id=%p", vp);
 		return;
+	}
 	pvr2_v4l2_destroy_no_lock(vp);
 }
 
@@ -946,7 +950,8 @@ static int pvr2_v4l2_release(struct file *file)
 	kfree(fhp);
 	if (vp->channel.mc_head->disconnect_flag &&
 	    list_empty(&vp->dev_video->devbase.fh_list) &&
-	    list_empty(&vp->dev_radio->devbase.fh_list)) {
+	    ((vp->dev_radio == NULL) ||
+	     list_empty(&vp->dev_radio->devbase.fh_list))) {
 		pvr2_v4l2_destroy_no_lock(vp);
 	}
 	return 0;
-- 
2.20.1

^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-11-06 11:18 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-06  2:36 [PATCH] pvrusb2: Fix oops on tear-down when radio support is not present 
2019-11-06  7:29 ` Hans Verkuil
2019-11-06 11:12   ` Mike Isely
2019-11-06 11:11 Mike Isely

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