diff mbox series

[net-next] net: phy: Fix suspicious rcu_dereference usage

Message ID 20250117141446.1076951-1-kory.maincent@bootlin.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next] net: phy: Fix suspicious rcu_dereference usage | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 0 this patch: 8
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 8 of 8 maintainers
netdev/build_clang fail Errors and warnings before: 1 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn fail Errors and warnings before: 0 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 39 this patch: 39
netdev/source_inline success Was 0 now: 0

Commit Message

Kory Maincent Jan. 17, 2025, 2:14 p.m. UTC 
The phy_detach function can be called with or without the rtnl lock held.
When the rtnl lock is not held, using rtnl_dereference() triggers a
warning due to the lack of lock context.

Add an rcu_read_lock() to ensure the lock is acquired and to maintain
synchronization.

Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reported-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Closes: https://lore.kernel.org/netdev/4c6419d8-c06b-495c-b987-d66c2e1ff848@tuxon.dev/
Fixes: 35f7cad1743e ("net: Add the possibility to support a selected hwtstamp in netdevice")
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
---
 drivers/net/phy/phy_device.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Kory Maincent Jan. 17, 2025, 5:09 p.m. UTC | #1 
On Fri, 17 Jan 2025 15:14:45 +0100
Kory Maincent <kory.maincent@bootlin.com> wrote:

> The phy_detach function can be called with or without the rtnl lock held.
> When the rtnl lock is not held, using rtnl_dereference() triggers a
> warning due to the lack of lock context.
> 
> Add an rcu_read_lock() to ensure the lock is acquired and to maintain
> synchronization.

Sent the wrong patch which have a ; missing.

pw-bot: cr

> 
> Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> Reported-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> Closes:
> https://lore.kernel.org/netdev/4c6419d8-c06b-495c-b987-d66c2e1ff848@tuxon.dev/
> Fixes: 35f7cad1743e ("net: Add the possibility to support a selected hwtstamp
> in netdevice") Signed-off-by: Kory Maincent <kory.maincent@bootlin.com> ---
>  drivers/net/phy/phy_device.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 5b34d39d1d52..b9b9aa16c10a 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -2001,12 +2001,14 @@ void phy_detach(struct phy_device *phydev)
>  	if (dev) {
>  		struct hwtstamp_provider *hwprov;
>  
> -		hwprov = rtnl_dereference(dev->hwprov);
> +		rcu_read_lock()
> +		hwprov = rcu_dereference(dev->hwprov);
>  		/* Disable timestamp if it is the one selected */
>  		if (hwprov && hwprov->phydev == phydev) {
>  			rcu_assign_pointer(dev->hwprov, NULL);
>  			kfree_rcu(hwprov, rcu_head);
>  		}
> +		rcu_read_unlock();
>  
>  		phydev->attached_dev->phydev = NULL;
>  		phydev->attached_dev = NULL;
diff mbox series

Patch

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 5b34d39d1d52..b9b9aa16c10a 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2001,12 +2001,14 @@  void phy_detach(struct phy_device *phydev)
 	if (dev) {
 		struct hwtstamp_provider *hwprov;
 
-		hwprov = rtnl_dereference(dev->hwprov);
+		rcu_read_lock()
+		hwprov = rcu_dereference(dev->hwprov);
 		/* Disable timestamp if it is the one selected */
 		if (hwprov && hwprov->phydev == phydev) {
 			rcu_assign_pointer(dev->hwprov, NULL);
 			kfree_rcu(hwprov, rcu_head);
 		}
+		rcu_read_unlock();
 
 		phydev->attached_dev->phydev = NULL;
 		phydev->attached_dev = NULL;