drivers/net/ethernet/broadcom/bcmsysport.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
Add error pointer checks in bcm_sysport_map_queues() and
bcm_sysport_unmap_queues() after calling dsa_port_from_netdev().
Fixes: 1593cd40d785 ("net: systemport: use standard netdevice notifier to detect DSA presence")
Signed-off-by: Dipendra Khadka <kdipendra88@gmail.com>
---
v5:
-Removed extra parentheses
v4: https://lore.kernel.org/all/20240925152927.4579-1-kdipendra88@gmail.com/
- Removed wrong and used correct Fixes: tag
v3: https://lore.kernel.org/all/20240924185634.2358-1-kdipendra88@gmail.com/
- Updated patch subject
- Updated patch description
- Added Fixes: tags
- Fixed typo from PRT_ERR to PTR_ERR
- Error is checked just after assignment
v2: https://lore.kernel.org/all/20240923053900.1310-1-kdipendra88@gmail.com/
- Change the subject of the patch to net
v1: https://lore.kernel.org/all/20240922181739.50056-1-kdipendra88@gmail.com/
drivers/net/ethernet/broadcom/bcmsysport.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
index c9faa8540859..a7ad829f11d4 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -2331,11 +2331,15 @@ static const struct net_device_ops bcm_sysport_netdev_ops = {
static int bcm_sysport_map_queues(struct net_device *dev,
struct net_device *slave_dev)
{
- struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
struct bcm_sysport_priv *priv = netdev_priv(dev);
struct bcm_sysport_tx_ring *ring;
unsigned int num_tx_queues;
unsigned int q, qp, port;
+ struct dsa_port *dp;
+
+ dp = dsa_port_from_netdev(slave_dev);
+ if (IS_ERR(dp))
+ return PTR_ERR(dp);
/* We can't be setting up queue inspection for non directly attached
* switches
@@ -2386,11 +2390,15 @@ static int bcm_sysport_map_queues(struct net_device *dev,
static int bcm_sysport_unmap_queues(struct net_device *dev,
struct net_device *slave_dev)
{
- struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
struct bcm_sysport_priv *priv = netdev_priv(dev);
struct bcm_sysport_tx_ring *ring;
unsigned int num_tx_queues;
unsigned int q, qp, port;
+ struct dsa_port *dp;
+
+ dp = dsa_port_from_netdev(slave_dev);
+ if (IS_ERR(dp))
+ return PTR_ERR(dp);
port = dp->index;
--
2.43.0+ Vladimir
On Thu, Sep 26, 2024 at 04:05:12PM +0000, Dipendra Khadka wrote:
> Add error pointer checks in bcm_sysport_map_queues() and
> bcm_sysport_unmap_queues() after calling dsa_port_from_netdev().
>
> Fixes: 1593cd40d785 ("net: systemport: use standard netdevice notifier to detect DSA presence")
> Signed-off-by: Dipendra Khadka <kdipendra88@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
> ---
> v5:
> -Removed extra parentheses
> v4: https://lore.kernel.org/all/20240925152927.4579-1-kdipendra88@gmail.com/
> - Removed wrong and used correct Fixes: tag
> v3: https://lore.kernel.org/all/20240924185634.2358-1-kdipendra88@gmail.com/
> - Updated patch subject
> - Updated patch description
> - Added Fixes: tags
> - Fixed typo from PRT_ERR to PTR_ERR
> - Error is checked just after assignment
> v2: https://lore.kernel.org/all/20240923053900.1310-1-kdipendra88@gmail.com/
> - Change the subject of the patch to net
> v1: https://lore.kernel.org/all/20240922181739.50056-1-kdipendra88@gmail.com/
> drivers/net/ethernet/broadcom/bcmsysport.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
> index c9faa8540859..a7ad829f11d4 100644
> --- a/drivers/net/ethernet/broadcom/bcmsysport.c
> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c
> @@ -2331,11 +2331,15 @@ static const struct net_device_ops bcm_sysport_netdev_ops = {
> static int bcm_sysport_map_queues(struct net_device *dev,
> struct net_device *slave_dev)
> {
> - struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
> struct bcm_sysport_priv *priv = netdev_priv(dev);
> struct bcm_sysport_tx_ring *ring;
> unsigned int num_tx_queues;
> unsigned int q, qp, port;
> + struct dsa_port *dp;
> +
> + dp = dsa_port_from_netdev(slave_dev);
> + if (IS_ERR(dp))
> + return PTR_ERR(dp);
>
> /* We can't be setting up queue inspection for non directly attached
> * switches
> @@ -2386,11 +2390,15 @@ static int bcm_sysport_map_queues(struct net_device *dev,
> static int bcm_sysport_unmap_queues(struct net_device *dev,
> struct net_device *slave_dev)
> {
> - struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
> struct bcm_sysport_priv *priv = netdev_priv(dev);
> struct bcm_sysport_tx_ring *ring;
> unsigned int num_tx_queues;
> unsigned int q, qp, port;
> + struct dsa_port *dp;
> +
> + dp = dsa_port_from_netdev(slave_dev);
> + if (IS_ERR(dp))
> + return PTR_ERR(dp);
>
> port = dp->index;
>
> --
> 2.43.0
>
On Fri, Sep 27, 2024 at 12:02:36PM +0100, Simon Horman wrote:
> + Vladimir
Thanks for adding me, Simon.
> On Thu, Sep 26, 2024 at 04:05:12PM +0000, Dipendra Khadka wrote:
> > Add error pointer checks in bcm_sysport_map_queues() and
> > bcm_sysport_unmap_queues() after calling dsa_port_from_netdev().
> >
> > Fixes: 1593cd40d785 ("net: systemport: use standard netdevice notifier to detect DSA presence")
> > Signed-off-by: Dipendra Khadka <kdipendra88@gmail.com>
>
> Reviewed-by: Simon Horman <horms@kernel.org>
>
> > ---
> > v5:
> > -Removed extra parentheses
> > v4: https://lore.kernel.org/all/20240925152927.4579-1-kdipendra88@gmail.com/
> > - Removed wrong and used correct Fixes: tag
> > v3: https://lore.kernel.org/all/20240924185634.2358-1-kdipendra88@gmail.com/
> > - Updated patch subject
> > - Updated patch description
> > - Added Fixes: tags
> > - Fixed typo from PRT_ERR to PTR_ERR
> > - Error is checked just after assignment
> > v2: https://lore.kernel.org/all/20240923053900.1310-1-kdipendra88@gmail.com/
> > - Change the subject of the patch to net
> > v1: https://lore.kernel.org/all/20240922181739.50056-1-kdipendra88@gmail.com/
> > drivers/net/ethernet/broadcom/bcmsysport.c | 12 ++++++++++--
> > 1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
> > index c9faa8540859..a7ad829f11d4 100644
> > --- a/drivers/net/ethernet/broadcom/bcmsysport.c
> > +++ b/drivers/net/ethernet/broadcom/bcmsysport.c
> > @@ -2331,11 +2331,15 @@ static const struct net_device_ops bcm_sysport_netdev_ops = {
> > static int bcm_sysport_map_queues(struct net_device *dev,
> > struct net_device *slave_dev)
> > {
> > - struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
> > struct bcm_sysport_priv *priv = netdev_priv(dev);
> > struct bcm_sysport_tx_ring *ring;
> > unsigned int num_tx_queues;
> > unsigned int q, qp, port;
> > + struct dsa_port *dp;
> > +
> > + dp = dsa_port_from_netdev(slave_dev);
> > + if (IS_ERR(dp))
> > + return PTR_ERR(dp);
> >
> > /* We can't be setting up queue inspection for non directly attached
> > * switches
> > @@ -2386,11 +2390,15 @@ static int bcm_sysport_map_queues(struct net_device *dev,
> > static int bcm_sysport_unmap_queues(struct net_device *dev,
> > struct net_device *slave_dev)
> > {
> > - struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
> > struct bcm_sysport_priv *priv = netdev_priv(dev);
> > struct bcm_sysport_tx_ring *ring;
> > unsigned int num_tx_queues;
> > unsigned int q, qp, port;
> > + struct dsa_port *dp;
> > +
> > + dp = dsa_port_from_netdev(slave_dev);
> > + if (IS_ERR(dp))
> > + return PTR_ERR(dp);
I don't see an explanation anywhere as for why dsa_port_from_netdev()
could ever return a pointer-encoded error here? hmm? Did you follow the
call path and found a problem?
On Fri, Sep 27, 2024 at 02:29:58PM +0300, Vladimir Oltean wrote:
> > > + dp = dsa_port_from_netdev(slave_dev);
> > > + if (IS_ERR(dp))
> > > + return PTR_ERR(dp);
>
> I don't see an explanation anywhere as for why dsa_port_from_netdev()
> could ever return a pointer-encoded error here? hmm? Did you follow the
> call path and found a problem?
To make my point even clearer. As the code goes:
bool dsa_user_dev_check(const struct net_device *dev)
{
// This dereferences "dev" without a NULL pointer check.
// If the kernel did not crash, it means that "dev" is not null.
return dev->netdev_ops == &dsa_user_netdev_ops;
}
static int bcm_sysport_netdevice_event(struct notifier_block *nb,
unsigned long event, void *ptr)
{
...
switch (event) {
case NETDEV_CHANGEUPPER:
...
if (!dsa_user_dev_check(info->upper_dev))
return NOTIFY_DONE;
// we know here that dsa_user_dev_check() is true, and
// no one changes dev->netdev_ops at runtime, to suspect
// it could become false after it just returned true.
// Even if it did, we are under rtnl_lock(), and whoever
// did that better also acquired rtnl_lock(). Thus,
// there is enough guarantee that this also remains true
// below.
if (info->linking)
ret = bcm_sysport_map_queues(dev, info->upper_dev);
else
ret = bcm_sysport_unmap_queues(dev, info->upper_dev);
}
...
}
struct dsa_port *dsa_port_from_netdev(struct net_device *netdev)
{
if (!netdev || !dsa_user_dev_check(netdev))
return ERR_PTR(-ENODEV);
return dsa_user_to_port(netdev);
}
static int bcm_sysport_map_queues(struct net_device *dev,
struct net_device *slave_dev)
{
struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
...
}
So, if both conditions for dsa_port_from_netdev() to return ERR_PTR(-ENODEV)
can only be false, why would we add an error check? Is it to appease a
static analysis tool which doesn't analyze things very far? Or is there
an actual problem?
And why does this have a Fixes: tag and the expectation to be included
as a bug fix to stable kernels?
And why is the author of the blamed patch even CCed only at v5?!
Hi Vladimir,
On Fri, 27 Sept 2024 at 17:45, Vladimir Oltean <vladimir.oltean@nxp.com> wrote:
>
> On Fri, Sep 27, 2024 at 02:29:58PM +0300, Vladimir Oltean wrote:
> > > > + dp = dsa_port_from_netdev(slave_dev);
> > > > + if (IS_ERR(dp))
> > > > + return PTR_ERR(dp);
> >
> > I don't see an explanation anywhere as for why dsa_port_from_netdev()
> > could ever return a pointer-encoded error here? hmm? Did you follow the
> > call path and found a problem?
>
Yeah, you are right. I ran smatch to find this and saw there is no
validation. I did not see any problem as you said. I thought it would
be better to include this change. If you say there is no point for
this change, then that's also fine for me. I got the chance to learn
new things.
> To make my point even clearer. As the code goes:
>
> bool dsa_user_dev_check(const struct net_device *dev)
> {
> // This dereferences "dev" without a NULL pointer check.
> // If the kernel did not crash, it means that "dev" is not null.
> return dev->netdev_ops == &dsa_user_netdev_ops;
> }
>
> static int bcm_sysport_netdevice_event(struct notifier_block *nb,
> unsigned long event, void *ptr)
> {
> ...
> switch (event) {
> case NETDEV_CHANGEUPPER:
> ...
> if (!dsa_user_dev_check(info->upper_dev))
> return NOTIFY_DONE;
>
> // we know here that dsa_user_dev_check() is true, and
> // no one changes dev->netdev_ops at runtime, to suspect
> // it could become false after it just returned true.
> // Even if it did, we are under rtnl_lock(), and whoever
> // did that better also acquired rtnl_lock(). Thus,
> // there is enough guarantee that this also remains true
> // below.
> if (info->linking)
> ret = bcm_sysport_map_queues(dev, info->upper_dev);
> else
> ret = bcm_sysport_unmap_queues(dev, info->upper_dev);
> }
> ...
> }
>
> struct dsa_port *dsa_port_from_netdev(struct net_device *netdev)
> {
> if (!netdev || !dsa_user_dev_check(netdev))
> return ERR_PTR(-ENODEV);
>
> return dsa_user_to_port(netdev);
> }
>
> static int bcm_sysport_map_queues(struct net_device *dev,
> struct net_device *slave_dev)
> {
> struct dsa_port *dp = dsa_port_from_netdev(slave_dev);
> ...
> }
>
> So, if both conditions for dsa_port_from_netdev() to return ERR_PTR(-ENODEV)
> can only be false, why would we add an error check? Is it to appease a
> static analysis tool which doesn't analyze things very far? Or is there
> an actual problem?
>
> And why does this have a Fixes: tag and the expectation to be included
> as a bug fix to stable kernels?
>
> And why is the author of the blamed patch even CCed only at v5?!
Sorry to know this, I ran the script and there I did not find your name.
./scripts/get_maintainer.pl drivers/net/ethernet/broadcom/bcmsysport.c
Florian Fainelli <florian.fainelli@broadcom.com> (supporter:BROADCOM
SYSTEMPORT ETHERNET DRIVER)
Broadcom internal kernel review list
<bcm-kernel-feedback-list@broadcom.com> (reviewer:BROADCOM SYSTEMPORT
ETHERNET DRIVER)
"David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING DRIVERS)
Eric Dumazet <edumazet@google.com> (maintainer:NETWORKING DRIVERS)
Jakub Kicinski <kuba@kernel.org> (maintainer:NETWORKING DRIVERS)
Paolo Abeni <pabeni@redhat.com> (maintainer:NETWORKING DRIVERS)
netdev@vger.kernel.org (open list:BROADCOM SYSTEMPORT ETHERNET DRIVER)
linux-kernel@vger.kernel.org (open list)
Thank you so much for your time and effort , special thanks to Simon
for everything ,thanks Vladimir for the way you explained. and thanks
Florian for your help.
Best regards,
Dipendra Khadka
On Mon, Sep 30, 2024 at 11:52:45PM +0545, Dipendra Khadka wrote: > > And why is the author of the blamed patch even CCed only at v5?! > > Sorry to know this, I ran the script and there I did not find your name. > > ./scripts/get_maintainer.pl drivers/net/ethernet/broadcom/bcmsysport.c > Florian Fainelli <florian.fainelli@broadcom.com> (supporter:BROADCOM SYSTEMPORT ETHERNET DRIVER) > Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com> (reviewer:BROADCOM SYSTEMPORT ETHERNET DRIVER) > "David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING DRIVERS) > Eric Dumazet <edumazet@google.com> (maintainer:NETWORKING DRIVERS) > Jakub Kicinski <kuba@kernel.org> (maintainer:NETWORKING DRIVERS) > Paolo Abeni <pabeni@redhat.com> (maintainer:NETWORKING DRIVERS) > netdev@vger.kernel.org (open list:BROADCOM SYSTEMPORT ETHERNET DRIVER) > linux-kernel@vger.kernel.org (open list) It's in the question you ask. Am I a maintainer of bcmsysport? No, and I haven't made significant contributions on it either. But if you run get_maintainer.pl on the _patch_ file that you will run through git send-email, my name will be listed (the "--fixes" option defaults to 1). The netdev CI also runs get_maintainers.pl on the actual patch, and that triggers one of its red flags: "1 blamed authors not CCed: vladimir.oltean@nxp.com" https://patchwork.kernel.org/project/netdevbpf/patch/20240926160513.7252-1-kdipendra88@gmail.com/
Hi, On Tue, 1 Oct 2024 at 02:17, Vladimir Oltean <vladimir.oltean@nxp.com> wrote: > > On Mon, Sep 30, 2024 at 11:52:45PM +0545, Dipendra Khadka wrote: > > > And why is the author of the blamed patch even CCed only at v5?! > > > > Sorry to know this, I ran the script and there I did not find your name. > > > > ./scripts/get_maintainer.pl drivers/net/ethernet/broadcom/bcmsysport.c > > Florian Fainelli <florian.fainelli@broadcom.com> (supporter:BROADCOM SYSTEMPORT ETHERNET DRIVER) > > Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com> (reviewer:BROADCOM SYSTEMPORT ETHERNET DRIVER) > > "David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING DRIVERS) > > Eric Dumazet <edumazet@google.com> (maintainer:NETWORKING DRIVERS) > > Jakub Kicinski <kuba@kernel.org> (maintainer:NETWORKING DRIVERS) > > Paolo Abeni <pabeni@redhat.com> (maintainer:NETWORKING DRIVERS) > > netdev@vger.kernel.org (open list:BROADCOM SYSTEMPORT ETHERNET DRIVER) > > linux-kernel@vger.kernel.org (open list) > > It's in the question you ask. Am I a maintainer of bcmsysport? No, and > I haven't made significant contributions on it either. But if you run > get_maintainer.pl on the _patch_ file that you will run through git > send-email, my name will be listed (the "--fixes" option defaults to 1). > Oh, thank you for this. I only used to run get_maintainers.pl on the file which got changed. I will run on the patch file as well from now. > The netdev CI also runs get_maintainers.pl on the actual patch, and that > triggers one of its red flags: "1 blamed authors not CCed: vladimir.oltean@nxp.com" > https://patchwork.kernel.org/project/netdevbpf/patch/20240926160513.7252-1-kdipendra88@gmail.com/ Best regards, Dipendra Khadka
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