From f86854a2e76256ee82025f981a5385480eec17b7 Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Wed, 16 Oct 2019 21:53:31 +0200 Subject: [PATCH] net: phy: avoid NPE if read_page/write_page callbacks are not available Currently there's a bug in the module subsystem [0] preventing load of the PHY driver module on certain systems (as one symptom). This results in a NPE on such systems for the following reason: Instead of the correct PHY driver the genphy driver is loaded that doesn't implement the read_page/write_page callbacks. Every call to phy_read_paged() et al will result in a NPE therefore. In parallel to fixing the root cause we should make sure that this one and maybe similar issues in other subsystems don't result in a NPE in phylib. So let's check for the callbacks before using them and warn once if they are not available. [0] https://marc.info/?t=157072642100001&r=1&w=2 Signed-off-by: Heiner Kallweit Signed-off-by: David S. Miller --- drivers/net/phy/phy-core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c index 4d96f7a8e8f2..5458ed1b87a8 100644 --- a/drivers/net/phy/phy-core.c +++ b/drivers/net/phy/phy-core.c @@ -697,11 +697,17 @@ EXPORT_SYMBOL_GPL(phy_modify_mmd); static int __phy_read_page(struct phy_device *phydev) { + if (WARN_ONCE(!phydev->drv->read_page, "read_page callback not available, PHY driver not loaded?\n")) + return -EOPNOTSUPP; + return phydev->drv->read_page(phydev); } static int __phy_write_page(struct phy_device *phydev, int page) { + if (WARN_ONCE(!phydev->drv->write_page, "write_page callback not available, PHY driver not loaded?\n")) + return -EOPNOTSUPP; + return phydev->drv->write_page(phydev, page); }