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    SubjectRe: [PATCH] wireless: Add missing locking to cfg80211_dev_rename
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    On Thu, 2008-05-08 at 14:30 -0700, Eric W. Biederman wrote:
    > device_rename only performs useful and race free validity
    > checking at the optional sysfs level so depending on it
    > for all of the validity checking in cfg80211_dev_rename
    > is racy.
    >
    > Instead implement all of the needed validity checking
    > and locking in cfg80211_dev_rename.

    Makes sense, thanks, I didn't really think about it not being compiled
    in.

    > Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

    Acked-by: Johannes Berg <johannes@sipsolutions.net>

    > ---
    > net/wireless/core.c | 33 ++++++++++++++++++++++++++++-----
    > 1 files changed, 28 insertions(+), 5 deletions(-)
    >
    > diff --git a/net/wireless/core.c b/net/wireless/core.c
    > index 80afacd..f1da0b9 100644
    > --- a/net/wireless/core.c
    > +++ b/net/wireless/core.c
    > @@ -143,8 +143,11 @@ void cfg80211_put_dev(struct cfg80211_registered_device *drv)
    > int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
    > char *newname)
    > {
    > + struct cfg80211_registered_device *drv;
    > int idx, taken = -1, result, digits;
    >
    > + mutex_lock(&cfg80211_drv_mutex);
    > +
    > /* prohibit calling the thing phy%d when %d is not its number */
    > sscanf(newname, PHY_NAME "%d%n", &idx, &taken);
    > if (taken == strlen(newname) && idx != rdev->idx) {
    > @@ -156,14 +159,30 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
    > * deny the name if it is phy<idx> where <idx> is printed
    > * without leading zeroes. taken == strlen(newname) here
    > */
    > + result = -EINVAL;
    > if (taken == strlen(PHY_NAME) + digits)
    > - return -EINVAL;
    > + goto out_unlock;
    > + }
    > +
    > +
    > + /* Ignore nop renames */
    > + result = 0;
    > + if (strcmp(newname, dev_name(&rdev->wiphy.dev)) == 0)
    > + goto out_unlock;
    > +
    > + /* Ensure another device does not already have this name. */
    > + list_for_each_entry(drv, &cfg80211_drv_list, list) {
    > + result = -EINVAL;
    > + if (strcmp(newname, dev_name(&drv->wiphy.dev)) == 0)
    > + goto out_unlock;
    > }
    >
    > - /* this will check for collisions */
    > + /* this will only check for collisions in sysfs
    > + * which is not even always compiled in.
    > + */
    > result = device_rename(&rdev->wiphy.dev, newname);
    > if (result)
    > - return result;
    > + goto out_unlock;
    >
    > if (!debugfs_rename(rdev->wiphy.debugfsdir->d_parent,
    > rdev->wiphy.debugfsdir,
    > @@ -172,9 +191,13 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
    > printk(KERN_ERR "cfg80211: failed to rename debugfs dir to %s!\n",
    > newname);
    >
    > - nl80211_notify_dev_rename(rdev);
    > + result = 0;
    > +out_unlock:
    > + mutex_unlock(&cfg80211_drv_mutex);
    > + if (result == 0)
    > + nl80211_notify_dev_rename(rdev);
    >
    > - return 0;
    > + return result;
    > }
    >
    > /* exported functions */
    [unhandled content-type:application/pgp-signature]
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