Commit fda6c89f authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller

net: mpls: fix stale pointer if allocation fails during device rename

lianhui reports that when MPLS fails to register the sysctl table
under new location (during device rename) the old pointers won't
get overwritten and may be freed again (double free).

Handle this gracefully. The best option would be unregistering
the MPLS from the device completely on failure, but unfortunately
mpls_ifdown() can fail. So failing fully is also unreliable.

Another option is to register the new table first then only
remove old one if the new one succeeds. That requires more
code, changes order of notifications and two tables may be
visible at the same time.

sysctl point is not used in the rest of the code - set to NULL
on failures and skip unregister if already NULL.
Reported-by: default avatarlianhui tang <bluetlh@gmail.com>
Fixes: 0fae3bf0 ("mpls: handle device renames for per-device sysctls")
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 42018a32
...@@ -1428,6 +1428,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev, ...@@ -1428,6 +1428,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
free: free:
kfree(table); kfree(table);
out: out:
mdev->sysctl = NULL;
return -ENOBUFS; return -ENOBUFS;
} }
...@@ -1437,6 +1438,9 @@ static void mpls_dev_sysctl_unregister(struct net_device *dev, ...@@ -1437,6 +1438,9 @@ static void mpls_dev_sysctl_unregister(struct net_device *dev,
struct net *net = dev_net(dev); struct net *net = dev_net(dev);
struct ctl_table *table; struct ctl_table *table;
if (!mdev->sysctl)
return;
table = mdev->sysctl->ctl_table_arg; table = mdev->sysctl->ctl_table_arg;
unregister_net_sysctl_table(mdev->sysctl); unregister_net_sysctl_table(mdev->sysctl);
kfree(table); kfree(table);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment