Hi,
I've been experimenting with kmemleak and noticed a recurring leak warning whenever I load & unload the qcserial driver.
Inspection of the code seems to indicate the leak is the serial->private data allocated in the qcprobe() function,
which is never freed (apart from in some of the qcprobe error paths) as far as I can tell.
The patch below fixes the following problems:
1 - Always free the serial->private data allocated in qcprobe, added a new function qc_release which frees the memory rather
than relying on the usb_wwan_release function which does not. Without this cleanup, we leak the memory allocated in qcprobe
when the kfree(serial) happens in usb-serial.c::destroy_serial()
2 - Ensure that the serial->private data is freed in the event of the probe failing and returning -ENODEV.
This error-path leak is less likely but still possible, it was discussed previously but not actually fixed AFAICS:
http://kerneltrap.org/mailarchive/linux-kernel/2010/6/14/4582980/thread,
http://lkml.org/lkml/2010/6/20/234
3 - Don't assign serial->private when doing the kzalloc or serial->private ends up pointing to freed memory in the event we return -ENODEV,
instead call usb_set_serial_data(serial, data) at the end of the function, and only have one return.
Please keep me on CC for any responses or review comments, since I'm not currently subscribed to LKML
Signed-off-by: Steve Hardy <[email protected]>
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 8858201..e66530a 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -111,7 +111,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
ifnum = intf->desc.bInterfaceNumber;
dbg("This Interface = %d", ifnum);
- data = serial->private = kzalloc(sizeof(struct usb_wwan_intf_private),
+ data = kzalloc(sizeof(struct usb_wwan_intf_private),
GFP_KERNEL);
if (!data)
return -ENOMEM;
@@ -134,8 +134,10 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
usb_endpoint_is_bulk_out(&intf->endpoint[1].desc)) {
dbg("QDL port found");
- if (serial->interface->num_altsetting == 1)
- return 0;
+ if (serial->interface->num_altsetting == 1) {
+ retval = 0; /* Success */
+ break;
+ }
retval = usb_set_interface(serial->dev, ifnum, 1);
if (retval < 0) {
@@ -145,7 +147,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
}
break;
@@ -166,6 +167,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
} else if (ifnum == 2) {
dbg("Modem port found");
@@ -177,7 +179,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
} else if (ifnum==3) {
/*
* NMEA (serial line 9600 8N1)
@@ -191,6 +192,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
}
break;
@@ -198,13 +200,27 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
default:
dev_err(&serial->dev->dev,
"unknown number of interfaces: %d\n", nintf);
+ retval = -ENODEV;
kfree(data);
- return -ENODEV;
}
+ /* Set serial->private may be null if -ENODEV */
+ usb_set_serial_data(serial, data);
return retval;
}
+static void qc_release(struct usb_serial *serial)
+{
+ struct usb_wwan_intf_private *priv = usb_get_serial_data(serial);
+
+ dbg("%s", __func__);
+
+ /* Call usb_wwan release & free the private data allocated in qcprobe */
+ usb_wwan_release(serial);
+ usb_set_serial_data(serial, NULL);
+ kfree(priv);
+}
+
static struct usb_serial_driver qcdevice = {
.driver = {
.owner = THIS_MODULE,
@@ -222,7 +238,7 @@ static struct usb_serial_driver qcdevice = {
.chars_in_buffer = usb_wwan_chars_in_buffer,
.attach = usb_wwan_startup,
.disconnect = usb_wwan_disconnect,
- .release = usb_wwan_release,
+ .release = qc_release,
#ifdef CONFIG_PM
.suspend = usb_wwan_suspend,
.resume = usb_wwan_resume,
On Mon, Mar 28, 2011 at 03:06:26PM +0100, Steven Hardy wrote:
> Hi,
>
> I've been experimenting with kmemleak and noticed a recurring leak warning whenever I load & unload the qcserial driver.
>
> Inspection of the code seems to indicate the leak is the serial->private data allocated in the qcprobe() function,
> which is never freed (apart from in some of the qcprobe error paths) as far as I can tell.
>
> The patch below fixes the following problems:
<snip>
Can you fix your email client to properly wrap your lines?
Also, as you do 3 different things here, can you break this into 3
patches and resend them?
thanks,
greg k-h
On Mon, Mar 28, 2011 at 07:21:48AM -0700, Greg KH wrote:
> On Mon, Mar 28, 2011 at 03:06:26PM +0100, Steven Hardy wrote:
> > Hi,
> >
> > I've been experimenting with kmemleak and noticed a recurring leak warning whenever I load & unload the qcserial driver.
> >
> > Inspection of the code seems to indicate the leak is the serial->private data allocated in the qcprobe() function,
> > which is never freed (apart from in some of the qcprobe error paths) as far as I can tell.
> >
> > The patch below fixes the following problems:
>
> <snip>
>
> Can you fix your email client to properly wrap your lines?
Apologies, was trying to avoid mangling the patch & ended up mangling the preamble instead, back to mutt now which will hopefully do the right thing! :)
> Also, as you do 3 different things here, can you break this into 3
> patches and resend them?
Done, please find patch 1 of 3 below:
The patch below fixes the following problem:
1 - Always free the serial->private data allocated in qcprobe, added a new function qc_release which frees the memory rather than relying on the usb_wwan_release function which does not. Without this cleanup, we leak the memory allocated in qcprobe when the kfree(serial) happens in usb-serial.c::destroy_serial()
Please keep me on CC for any responses or review comments, since I'm not currently subscribed to LKML
Signed-off-by: Steve Hardy <[email protected]>
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 8858201..6e3b933 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -205,6 +205,18 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
return retval;
}
+static void qc_release(struct usb_serial *serial)
+{
+ struct usb_wwan_intf_private *priv = usb_get_serial_data(serial);
+
+ dbg("%s", __func__);
+
+ /* Call usb_wwan release & free the private data allocated in qcprobe */
+ usb_wwan_release(serial);
+ usb_set_serial_data(serial, NULL);
+ kfree(priv);
+}
+
static struct usb_serial_driver qcdevice = {
.driver = {
.owner = THIS_MODULE,
@@ -222,7 +234,7 @@ static struct usb_serial_driver qcdevice = {
.chars_in_buffer = usb_wwan_chars_in_buffer,
.attach = usb_wwan_startup,
.disconnect = usb_wwan_disconnect,
- .release = usb_wwan_release,
+ .release = qc_release,
#ifdef CONFIG_PM
.suspend = usb_wwan_suspend,
.resume = usb_wwan_resume,
On Mon, Mar 28, 2011 at 03:06:26PM +0100, Steven Hardy wrote:
> @@ -198,13 +200,27 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
> default:
> dev_err(&serial->dev->dev,
> "unknown number of interfaces: %d\n", nintf);
> + retval = -ENODEV;
> kfree(data);
> - return -ENODEV;
> }
>
> + /* Set serial->private may be null if -ENODEV */
> + usb_set_serial_data(serial, data);
> return retval;
> }
when there's a -ENODEV, kfree() is called but the now invalid address is
set by usb_set_serial_data() anyway. am I missing something here?
--
Aristeu
Patch 2 of 3, addresses the problem where serial->private can end up pointing to freed memory in the event qcprobe fails & returns -ENODEV
Original description:
3 - Don't assign serial->private when doing the kzalloc or serial->private ends up pointing to freed memory in the event we return -ENODEV, instead call usb_set_serial_data(serial, data) at the end of the function, and only have one return-point.
Signed-off-by: Steve Hardy <[email protected]>
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 6e3b933..0463dab 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -111,7 +111,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
ifnum = intf->desc.bInterfaceNumber;
dbg("This Interface = %d", ifnum);
- data = serial->private = kzalloc(sizeof(struct usb_wwan_intf_private),
+ data = kzalloc(sizeof(struct usb_wwan_intf_private),
GFP_KERNEL);
if (!data)
return -ENOMEM;
@@ -134,8 +134,10 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
usb_endpoint_is_bulk_out(&intf->endpoint[1].desc)) {
dbg("QDL port found");
- if (serial->interface->num_altsetting == 1)
- return 0;
+ if (serial->interface->num_altsetting == 1) {
+ retval = 0; /* Success */
+ break;
+ }
retval = usb_set_interface(serial->dev, ifnum, 1);
if (retval < 0) {
@@ -145,7 +147,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
}
break;
@@ -177,7 +178,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
} else if (ifnum==3) {
/*
* NMEA (serial line 9600 8N1)
@@ -199,9 +199,11 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
dev_err(&serial->dev->dev,
"unknown number of interfaces: %d\n", nintf);
kfree(data);
- return -ENODEV;
+ retval = -ENODEV;
}
+ /* Set serial->private may be null if -ENODEV */
+ usb_set_serial_data(serial, data);
return retval;
}
Patch 3 of 3, this simply adds a couple of missing free's in the error path:
Original description:
2 - Ensure that the serial->private data is freed in the event of the probe failing and returning -ENODEV. This error-path leak is less likely but still possible, it was discussed previously but not actually fixed AFAICS: http://kerneltrap.org/mailarchive/linux-kernel/2010/6/14/4582980/thread, http://lkml.org/lkml/2010/6/20/234
Signed-off-by: Steve Hardy <[email protected]>
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 0463dab..6219fce 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -167,6 +167,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
} else if (ifnum == 2) {
dbg("Modem port found");
@@ -191,6 +192,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
}
break;
On Mon, Mar 28, 2011 at 01:34:24PM -0400, Aristeu Rozanski wrote:
> > + usb_set_serial_data(serial, data);
> > return retval;
> > }
> when there's a -ENODEV, kfree() is called but the now invalid address is
> set by usb_set_serial_data() anyway. am I missing something here?
The intention here is that since data should be NULL after the kfree, we're simply setting serial->private to NULL.
I can add a conditional to avoid calling usb_set_serial_data() for -ENODEV if it's deemed cleaner or more readable.
Thanks for the comments,
Steve
On Mon, Mar 28, 2011 at 06:48:11PM +0100, Steven Hardy wrote:
> On Mon, Mar 28, 2011 at 01:34:24PM -0400, Aristeu Rozanski wrote:
> > > + usb_set_serial_data(serial, data);
> > > return retval;
> > > }
> > when there's a -ENODEV, kfree() is called but the now invalid address is
> > set by usb_set_serial_data() anyway. am I missing something here?
>
> The intention here is that since data should be NULL after the kfree, we're simply setting serial->private to NULL.
kfree(data) won't make data == NULL. it'll free whatever address data
has. data will still have the same (now stale) address. you need to
explicitely make data = NULL if you want that behavior.
--
Aristeu
On Mon, Mar 28, 2011 at 01:54:48PM -0400, Aristeu Rozanski wrote:
> kfree(data) won't make data == NULL. it'll free whatever address data
> has. data will still have the same (now stale) address. you need to
> explicitely make data = NULL if you want that behavior.
Of course, sorry I should have remembered that, too much scripting lately's caused some brain-rot :)
I will resend a revised patch.
Thanks,
Steve
Second draft of patch #2, this addresses the review comments made by Aristeu Rozanski, now usb_set_serial_data() is only called when we are not returning -ENODEV
Original description:
Don't assign serial->private when doing the kzalloc or serial->private ends up pointing to freed memory in the event we return -ENODEV, instead call usb_set_serial_data(serial, data) at the end of the function, and only have one return-point.
Signed-off-by: Steve Hardy <[email protected]>
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 6e3b933..b9b97ad 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -111,7 +111,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
ifnum = intf->desc.bInterfaceNumber;
dbg("This Interface = %d", ifnum);
- data = serial->private = kzalloc(sizeof(struct usb_wwan_intf_private),
+ data = kzalloc(sizeof(struct usb_wwan_intf_private),
GFP_KERNEL);
if (!data)
return -ENOMEM;
@@ -134,8 +134,10 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
usb_endpoint_is_bulk_out(&intf->endpoint[1].desc)) {
dbg("QDL port found");
- if (serial->interface->num_altsetting == 1)
- return 0;
+ if (serial->interface->num_altsetting == 1) {
+ retval = 0; /* Success */
+ break;
+ }
retval = usb_set_interface(serial->dev, ifnum, 1);
if (retval < 0) {
@@ -145,7 +147,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
}
break;
@@ -177,7 +178,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
} else if (ifnum==3) {
/*
* NMEA (serial line 9600 8N1)
@@ -199,9 +199,12 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
dev_err(&serial->dev->dev,
"unknown number of interfaces: %d\n", nintf);
kfree(data);
- return -ENODEV;
+ retval = -ENODEV;
}
+ /* Set serial->private if not returning -ENODEV */
+ if ( retval != -ENODEV )
+ usb_set_serial_data(serial, data);
return retval;
}
Hello.
On 28-03-2011 21:38, Steven Hardy wrote:
Posting all 3 patches having the same sucject is not a good idea.
> Patch 2 of 3, addresses the problem where serial->private can end up pointing to freed memory in the event qcprobe fails & returns -ENODEV
You still didn't wrap the changelog text properly.
> Original description:
> 3 - Don't assign serial->private when doing the kzalloc or serial->private ends up pointing to freed memory in the event we return -ENODEV, instead call usb_set_serial_data(serial, data) at the end of the function, and only have one return-point.
WBR, Sergei
Hello.
On 29-03-2011 2:16, Steven Hardy wrote:
> Second draft of patch #2, this addresses the review comments made by Aristeu Rozanski, now usb_set_serial_data() is only called when we are not returning -ENODEV
Such comments should be put under --- tearline (which should appear under
your signoff). Otherwise Greg will have to hand edit them out of your patch.
> Original description:
Omit that please.
> Don't assign serial->private when doing the kzalloc or serial->private ends up pointing to freed memory in the event we return -ENODEV, instead call usb_set_serial_data(serial, data) at the end of the function, and only have one return-point.
Still not properly wrapped.
> Signed-off-by: Steve Hardy<[email protected]>
> diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
> index 6e3b933..b9b97ad 100644
> --- a/drivers/usb/serial/qcserial.c
> +++ b/drivers/usb/serial/qcserial.c
[...]
> @@ -199,9 +199,12 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
> dev_err(&serial->dev->dev,
> "unknown number of interfaces: %d\n", nintf);
> kfree(data);
> - return -ENODEV;
> + retval = -ENODEV;
> }
>
> + /* Set serial->private if not returning -ENODEV */
> + if ( retval != -ENODEV )
No spaces after ( and before ) allowed.
WBR, Sergei
On Mon, Mar 28, 2011 at 11:16:37PM +0100, Steven Hardy wrote:
> + /* Set serial->private if not returning -ENODEV */
> + if ( retval != -ENODEV )
^ ^
coding style
> + usb_set_serial_data(serial, data);
> return retval;
> }
the rest looks good to me.
--
Aristeu
qcprobe function allocates serial->private but this is never freed, this
patch adds a new function qc_release() which frees serial->private, after
calling usb_wwan_release
Signed-off-by: Steven Hardy <[email protected]>
---
Repost of qcserial patches posted last week, hopefully addresses review
comments and email-patch-format issues
drivers/usb/serial/qcserial.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 8858201..6e3b933 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -205,6 +205,18 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
return retval;
}
+static void qc_release(struct usb_serial *serial)
+{
+ struct usb_wwan_intf_private *priv = usb_get_serial_data(serial);
+
+ dbg("%s", __func__);
+
+ /* Call usb_wwan release & free the private data allocated in qcprobe */
+ usb_wwan_release(serial);
+ usb_set_serial_data(serial, NULL);
+ kfree(priv);
+}
+
static struct usb_serial_driver qcdevice = {
.driver = {
.owner = THIS_MODULE,
@@ -222,7 +234,7 @@ static struct usb_serial_driver qcdevice = {
.chars_in_buffer = usb_wwan_chars_in_buffer,
.attach = usb_wwan_startup,
.disconnect = usb_wwan_disconnect,
- .release = usb_wwan_release,
+ .release = qc_release,
#ifdef CONFIG_PM
.suspend = usb_wwan_suspend,
.resume = usb_wwan_resume,
--
1.7.1
Rework the qcprobe logic such that serial->private is not set when
qcprobe exits with -ENODEV, otherwise serial->private will point to freed
memory on -ENODEV
Signed-off-by: Steven Hardy <[email protected]>
---
Repost of qcserial patches posted last week, hopefully addresses review
comments and email-patch-format issues
drivers/usb/serial/qcserial.c | 15 +++++++++------
1 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index 6e3b933..cd63864 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -111,7 +111,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
ifnum = intf->desc.bInterfaceNumber;
dbg("This Interface = %d", ifnum);
- data = serial->private = kzalloc(sizeof(struct usb_wwan_intf_private),
+ data = kzalloc(sizeof(struct usb_wwan_intf_private),
GFP_KERNEL);
if (!data)
return -ENOMEM;
@@ -134,8 +134,10 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
usb_endpoint_is_bulk_out(&intf->endpoint[1].desc)) {
dbg("QDL port found");
- if (serial->interface->num_altsetting == 1)
- return 0;
+ if (serial->interface->num_altsetting == 1) {
+ retval = 0; /* Success */
+ break;
+ }
retval = usb_set_interface(serial->dev, ifnum, 1);
if (retval < 0) {
@@ -145,7 +147,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
}
break;
@@ -177,7 +178,6 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
retval = -ENODEV;
kfree(data);
}
- return retval;
} else if (ifnum==3) {
/*
* NMEA (serial line 9600 8N1)
@@ -199,9 +199,12 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
dev_err(&serial->dev->dev,
"unknown number of interfaces: %d\n", nintf);
kfree(data);
- return -ENODEV;
+ retval = -ENODEV;
}
+ /* Set serial->private if not returning -ENODEV */
+ if (retval != -ENODEV)
+ usb_set_serial_data(serial, data);
return retval;
}
--
1.7.1
There are two -ENODEV error paths in qcprobe where the allocated private
data is not freed, this patch adds the two missing kfrees to avoid
leaking memory on the error path
Signed-off-by: Steven Hardy <[email protected]>
---
Repost of qcserial patches posted last week, hopefully addresses review
comments and email-patch-format issues
drivers/usb/serial/qcserial.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/serial/qcserial.c b/drivers/usb/serial/qcserial.c
index cd63864..54a9dab 100644
--- a/drivers/usb/serial/qcserial.c
+++ b/drivers/usb/serial/qcserial.c
@@ -167,6 +167,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
} else if (ifnum == 2) {
dbg("Modem port found");
@@ -191,6 +192,7 @@ static int qcprobe(struct usb_serial *serial, const struct usb_device_id *id)
"Could not set interface, error %d\n",
retval);
retval = -ENODEV;
+ kfree(data);
}
}
break;
--
1.7.1