[28/30] bonding: fix a race condition in calls to slave MII ioctls

[Greg KH]

2.6.29-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Jiri Bohac <jbohac@xxxxxxx>

commit d9d5283228d0c752f199c901fff6e1405dc91bcb upstream.

In mii monitor mode, bond_check_dev_link() calls the the ioctl
handler of slave devices. It stores the ndo_do_ioctl function
pointer to a static (!) ioctl variable and later uses it to call the
handler with the IOCTL macro.

If another thread executes bond_check_dev_link() at the same time
(even with a different bond, which none of the locks prevent), a
race condition occurs. If the two racing slaves have different
drivers, this may result in one driver's ioctl handler being
called with a pointer to a net_device controlled with a different
driver, resulting in unpredictable breakage.

Unless I am overlooking something, the "static" must be a
copy'n'paste error (?).

Signed-off-by: Jiri Bohac <jbohac@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/net/bonding/bond_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -686,7 +686,7 @@ static int bond_update_speed_duplex(stru
  */
 static int bond_check_dev_link(struct bonding *bond, struct net_device *slave_dev, int reporting)
 {
-	static int (* ioctl)(struct net_device *, struct ifreq *, int);
+	int (* ioctl)(struct net_device *, struct ifreq *, int);
 	struct ifreq ifr;
 	struct mii_ioctl_data *mii;
 


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