[net-next v5 0/2] Prevent nullptr exceptions in ISR

[net-next v5 0/2] Prevent nullptr exceptions in ISR

[Andre Werner]

In case phydev->irq is modified unconditionally to a valid IRQ, handling
the IRQ may lead to a nullptr exception if no interrupt handler is
registered to the phy driver. phy_interrupt calls a
phy_device->handle_interrupt unconditionally. And interrupts are enabled
in phy_connect_direct if phydev->irq is not equal to PHY_POLL or
PHY_MAC_INTERRUPT, so it does not check for a phy driver providing an ISR.

Adding an additonal check for a valid interrupt handler in phy_attach_direct
function, and falling back to polling mode if not, should prevent for
such nullptr exceptions.

Moreover, the ADIN1100 phy driver is extended with an interrupt handler
for changes in the link status.

Andre Werner (2):
  net: phy: phy_device: Prevent nullptr exceptions on ISR
  net: phy: adin1100: Add interrupt support for link change

 drivers/net/phy/adin1100.c   | 55 ++++++++++++++++++++++++++++++++++++
 drivers/net/phy/phy_device.c | 13 +++++----
 2 files changed, 63 insertions(+), 5 deletions(-)

-- 
2.43.0

[net-next v5 1/2] net: phy: phy_device: Prevent nullptr exceptions on ISR

[Andre Werner]

If phydev->irq is set unconditionally, check
for valid interrupt handler or fall back to polling mode to prevent
nullptr exceptions in interrupt service routine.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
v5:
- No functional changes. Add Reviewed-by tag.

v4:
- Delete phydev_warn and comment as suggested.

v3:
- No changes to v2. Just to complete the series.

v2:
- Add changes suggested in discussion about adin1100.c driver to
  phy_attach_direct.
---
 drivers/net/phy/phy_device.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index dd778c7fde1d..52828d1c64f7 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1413,6 +1413,11 @@ int phy_sfp_probe(struct phy_device *phydev,
 }
 EXPORT_SYMBOL(phy_sfp_probe);
 
+static bool phy_drv_supports_irq(struct phy_driver *phydrv)
+{
+	return phydrv->config_intr && phydrv->handle_interrupt;
+}
+
 /**
  * phy_attach_direct - attach a network device to a given PHY device pointer
  * @dev: network device to attach
@@ -1527,6 +1532,9 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	if (phydev->dev_flags & PHY_F_NO_IRQ)
 		phydev->irq = PHY_POLL;
 
+	if (!phy_drv_supports_irq(phydev->drv) && phy_interrupt_is_valid(phydev))
+		phydev->irq = PHY_POLL;
+
 	/* Port is set to PORT_TP by default and the actual PHY driver will set
 	 * it to different value depending on the PHY configuration. If we have
 	 * the generic PHY driver we can't figure it out, thus set the old
@@ -2992,11 +3000,6 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 }
 EXPORT_SYMBOL(phy_get_internal_delay);
 
-static bool phy_drv_supports_irq(struct phy_driver *phydrv)
-{
-	return phydrv->config_intr && phydrv->handle_interrupt;
-}
-
 static int phy_led_set_brightness(struct led_classdev *led_cdev,
 				  enum led_brightness value)
 {
-- 
2.43.0

Re: [net-next v5 1/2] net: phy: phy_device: Prevent nullptr exceptions on ISR

[Andrew Lunn]

On Mon, Jan 29, 2024 at 02:55:04PM +0100, Andre Werner wrote:
> If phydev->irq is set unconditionally, check
> for valid interrupt handler or fall back to polling mode to prevent
> nullptr exceptions in interrupt service routine.
> 
> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>

Nitpick:

Your Signed-off-by: should go last.

Its not enough to need a respin, but please keep this in mind for
future patches.

       Andrew

Re: [net-next v5 1/2] net: phy: phy_device: Prevent nullptr exceptions on ISR

[Andre Werner]

Thanks Andrew,

I will keep this in mind. Sorry!

Andre


On Mon, 29 Jan 2024, Andrew Lunn wrote:

> On Mon, Jan 29, 2024 at 02:55:04PM +0100, Andre Werner wrote:
>> If phydev->irq is set unconditionally, check
>> for valid interrupt handler or fall back to polling mode to prevent
>> nullptr exceptions in interrupt service routine.
>>
>> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
>> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
>
> Nitpick:
>
> Your Signed-off-by: should go last.
>
> Its not enough to need a respin, but please keep this in mind for
> future patches.
>
>       Andrew
>

[net-next v5 2/2] net: phy: adin1100: Add interrupt support for link change

[Andre Werner]

An interrupt handler was added to the driver as well as functions
to enable interrupts at the phy.

There are several interrupts maskable at the phy, but only link change
interrupts are handled by the driver yet.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
---
v5:
- Add reversed-x-max-notation to variables in adin_config_intr.
- Delete empty line between function call and if statement.

v4:
- Change read-modify-write behavior as suggested to phy_modify_mmd.

v3:
- Correct rashly format error that was reported by checker.

v2:
- Clean format and reword commit message as suggested by reviewer of
  first patch submission
---
 drivers/net/phy/adin1100.c | 55 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/net/phy/adin1100.c b/drivers/net/phy/adin1100.c
index 7619d6185801..85f910e2d4fb 100644
--- a/drivers/net/phy/adin1100.c
+++ b/drivers/net/phy/adin1100.c
@@ -18,6 +18,12 @@
 #define PHY_ID_ADIN1110				0x0283bc91
 #define PHY_ID_ADIN2111				0x0283bca1
 
+#define ADIN_PHY_SUBSYS_IRQ_MASK		0x0021
+#define   ADIN_LINK_STAT_CHNG_IRQ_EN		BIT(1)
+
+#define ADIN_PHY_SUBSYS_IRQ_STATUS		0x0011
+#define   ADIN_LINK_STAT_CHNG			BIT(1)
+
 #define ADIN_FORCED_MODE			0x8000
 #define   ADIN_FORCED_MODE_EN			BIT(0)
 
@@ -136,6 +142,53 @@ static int adin_config_aneg(struct phy_device *phydev)
 	return genphy_c45_config_aneg(phydev);
 }
 
+static int adin_phy_ack_intr(struct phy_device *phydev)
+{
+	/* Clear pending interrupts */
+	int rc = phy_read_mmd(phydev, MDIO_MMD_VEND2,
+			      ADIN_PHY_SUBSYS_IRQ_STATUS);
+
+	return rc < 0 ? rc : 0;
+}
+
+static int adin_config_intr(struct phy_device *phydev)
+{
+	u16 irq_mask;
+	int ret;
+
+	ret = adin_phy_ack_intr(phydev);
+	if (ret)
+		return ret;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED)
+		irq_mask = ADIN_LINK_STAT_CHNG_IRQ_EN;
+	else
+		irq_mask = 0;
+
+	return phy_modify_mmd(phydev, MDIO_MMD_VEND2,
+			      ADIN_PHY_SUBSYS_IRQ_MASK,
+			      ADIN_LINK_STAT_CHNG_IRQ_EN, irq_mask);
+}
+
+static irqreturn_t adin_phy_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read_mmd(phydev, MDIO_MMD_VEND2,
+				  ADIN_PHY_SUBSYS_IRQ_STATUS);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & ADIN_LINK_STAT_CHNG))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
 static int adin_set_powerdown_mode(struct phy_device *phydev, bool en)
 {
 	int ret;
@@ -275,6 +328,8 @@ static struct phy_driver adin_driver[] = {
 		.probe			= adin_probe,
 		.config_aneg		= adin_config_aneg,
 		.read_status		= adin_read_status,
+		.config_intr		= adin_config_intr,
+		.handle_interrupt	= adin_phy_handle_interrupt,
 		.set_loopback		= adin_set_loopback,
 		.suspend		= adin_suspend,
 		.resume			= adin_resume,
-- 
2.43.0

Re: [net-next v5 0/2] Prevent nullptr exceptions in ISR

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 29 Jan 2024 14:55:03 +0100 you wrote:
> In case phydev->irq is modified unconditionally to a valid IRQ, handling
> the IRQ may lead to a nullptr exception if no interrupt handler is
> registered to the phy driver. phy_interrupt calls a
> phy_device->handle_interrupt unconditionally. And interrupts are enabled
> in phy_connect_direct if phydev->irq is not equal to PHY_POLL or
> PHY_MAC_INTERRUPT, so it does not check for a phy driver providing an ISR.
> 
> [...]

Here is the summary with links:
  - [net-next,v5,1/2] net: phy: phy_device: Prevent nullptr exceptions on ISR
    https://git.kernel.org/netdev/net-next/c/61c81872815f
  - [net-next,v5,2/2] net: phy: adin1100: Add interrupt support for link change
    https://git.kernel.org/netdev/net-next/c/08b47dfdd6b8

You are awesome, thank you!
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