netdev - Re: [PATCH net-next 1/7] net: phy: always call phy_process_state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZQhLUlw452Ewu7yi@shell.armlinux.org.uk>
Date: Mon, 18 Sep 2023 14:06:26 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	chenhao418@...wei.com, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Jijie Shao <shaojijie@...wei.com>,
	lanhao@...wei.com, liuyonglong@...wei.com, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>, shenjian15@...wei.com,
	wangjie125@...wei.com, wangpeiyang1@...wei.com
Subject: Re: [PATCH net-next 1/7] net: phy: always call
 phy_process_state_change() under lock

On Mon, Sep 18, 2023 at 02:33:04PM +0200, Marek Szyprowski wrote:
> Hi Russell,
> 
> On 14.09.2023 17:35, Russell King (Oracle) wrote:
> > phy_stop() calls phy_process_state_change() while holding the phydev
> > lock, so also arrange for phy_state_machine() to do the same, so that
> > this function is called with consistent locking.
> >
> > Tested-by: Jijie Shao <shaojijie@...wei.com>
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> 
> This change, merged to linux-next as commit 8da77df649c4 ("net: phy: 
> always call phy_process_state_change() under lock") introduces the 
> following deadlock with ASIX AX8817X USB driver:

Yay, latent bug found...

I guess this is asix_ax88772a_link_change_notify() which is causing
the problem, and yes, that phy_start_aneg() needs to be the unlocked
version (which we'll have to export.)

This should fix it.

diff --git a/drivers/net/phy/ax88796b.c b/drivers/net/phy/ax88796b.c
index 0f1e617a26c9..eb74a8cf8df1 100644
--- a/drivers/net/phy/ax88796b.c
+++ b/drivers/net/phy/ax88796b.c
@@ -90,7 +90,7 @@ static void asix_ax88772a_link_change_notify(struct phy_device *phydev)
 	 */
 	if (phydev->state == PHY_NOLINK) {
 		phy_init_hw(phydev);
-		phy_start_aneg(phydev);
+		_phy_start_aneg(phydev);
 	}
 }
 
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 93a8676dd8d8..a5fa077650e8 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -981,7 +981,7 @@ static int phy_check_link_status(struct phy_device *phydev)
  *   If the PHYCONTROL Layer is operating, we change the state to
  *   reflect the beginning of Auto-negotiation or forcing.
  */
-static int _phy_start_aneg(struct phy_device *phydev)
+int _phy_start_aneg(struct phy_device *phydev)
 {
 	int err;
 
@@ -1002,6 +1002,7 @@ static int _phy_start_aneg(struct phy_device *phydev)
 
 	return err;
 }
+EXPORT_SYMBOL(_phy_start_aneg);
 
 /**
  * phy_start_aneg - start auto-negotiation for this PHY device
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 1351b802ffcf..3cc52826f18e 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1736,6 +1736,7 @@ void phy_detach(struct phy_device *phydev);
 void phy_start(struct phy_device *phydev);
 void phy_stop(struct phy_device *phydev);
 int phy_config_aneg(struct phy_device *phydev);
+int _phy_start_aneg(struct phy_device *phydev);
 int phy_start_aneg(struct phy_device *phydev);
 int phy_aneg_done(struct phy_device *phydev);
 int phy_speed_down(struct phy_device *phydev, bool sync);
-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!