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Date: Wed, 15 Mar 2017 14:29:13 +0100
From: Johannes Berg <johannes@...solutions.net>
To: linux-wireless@...r.kernel.org
Cc: netdev@...r.kernel.org,
Sowmini Varadhan <sowmini.varadhan@...cle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH] nl80211: fix dumpit error path RTNL deadlocks
From: Johannes Berg <johannes.berg@...el.com>
Sowmini pointed out Dmitry's RTNL deadlock report to me, and it turns out
to be perfectly accurate - there are various error paths that miss unlock
of the RTNL.
To fix those, change the locking a bit to not be conditional in all those
nl80211_prepare_*_dump() functions, but make those require the RTNL to
start with, and fix the buggy error paths. This also let me use sparse
(by appropriately overriding the rtnl_lock/rtnl_unlock functions) to
validate the changes.
Reported-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
net/wireless/nl80211.c | 127 ++++++++++++++++++++++---------------------------
1 file changed, 56 insertions(+), 71 deletions(-)
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index b15903b9c0ab..26192275e596 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -545,22 +545,18 @@ static int nl80211_prepare_wdev_dump(struct sk_buff *skb,
{
int err;
- rtnl_lock();
-
if (!cb->args[0]) {
err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
genl_family_attrbuf(&nl80211_fam),
nl80211_fam.maxattr, nl80211_policy);
if (err)
- goto out_unlock;
+ return err;
*wdev = __cfg80211_wdev_from_attrs(
sock_net(skb->sk),
genl_family_attrbuf(&nl80211_fam));
- if (IS_ERR(*wdev)) {
- err = PTR_ERR(*wdev);
- goto out_unlock;
- }
+ if (IS_ERR(*wdev))
+ return PTR_ERR(*wdev);
*rdev = wiphy_to_rdev((*wdev)->wiphy);
/* 0 is the first index - add 1 to parse only once */
cb->args[0] = (*rdev)->wiphy_idx + 1;
@@ -570,10 +566,8 @@ static int nl80211_prepare_wdev_dump(struct sk_buff *skb,
struct wiphy *wiphy = wiphy_idx_to_wiphy(cb->args[0] - 1);
struct wireless_dev *tmp;
- if (!wiphy) {
- err = -ENODEV;
- goto out_unlock;
- }
+ if (!wiphy)
+ return -ENODEV;
*rdev = wiphy_to_rdev(wiphy);
*wdev = NULL;
@@ -584,21 +578,11 @@ static int nl80211_prepare_wdev_dump(struct sk_buff *skb,
}
}
- if (!*wdev) {
- err = -ENODEV;
- goto out_unlock;
- }
+ if (!*wdev)
+ return -ENODEV;
}
return 0;
- out_unlock:
- rtnl_unlock();
- return err;
-}
-
-static void nl80211_finish_wdev_dump(struct cfg80211_registered_device *rdev)
-{
- rtnl_unlock();
}
/* IE validation */
@@ -2608,17 +2592,17 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
int filter_wiphy = -1;
struct cfg80211_registered_device *rdev;
struct wireless_dev *wdev;
+ int ret;
rtnl_lock();
if (!cb->args[2]) {
struct nl80211_dump_wiphy_state state = {
.filter_wiphy = -1,
};
- int ret;
ret = nl80211_dump_wiphy_parse(skb, cb, &state);
if (ret)
- return ret;
+ goto out_unlock;
filter_wiphy = state.filter_wiphy;
@@ -2663,12 +2647,14 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
wp_idx++;
}
out:
- rtnl_unlock();
-
cb->args[0] = wp_idx;
cb->args[1] = if_idx;
- return skb->len;
+ ret = skb->len;
+ out_unlock:
+ rtnl_unlock();
+
+ return ret;
}
static int nl80211_get_interface(struct sk_buff *skb, struct genl_info *info)
@@ -4452,9 +4438,10 @@ static int nl80211_dump_station(struct sk_buff *skb,
int sta_idx = cb->args[2];
int err;
+ rtnl_lock();
err = nl80211_prepare_wdev_dump(skb, cb, &rdev, &wdev);
if (err)
- return err;
+ goto out_err;
if (!wdev->netdev) {
err = -EINVAL;
@@ -4489,7 +4476,7 @@ static int nl80211_dump_station(struct sk_buff *skb,
cb->args[2] = sta_idx;
err = skb->len;
out_err:
- nl80211_finish_wdev_dump(rdev);
+ rtnl_unlock();
return err;
}
@@ -5275,9 +5262,10 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
int path_idx = cb->args[2];
int err;
+ rtnl_lock();
err = nl80211_prepare_wdev_dump(skb, cb, &rdev, &wdev);
if (err)
- return err;
+ goto out_err;
if (!rdev->ops->dump_mpath) {
err = -EOPNOTSUPP;
@@ -5310,7 +5298,7 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
cb->args[2] = path_idx;
err = skb->len;
out_err:
- nl80211_finish_wdev_dump(rdev);
+ rtnl_unlock();
return err;
}
@@ -5470,9 +5458,10 @@ static int nl80211_dump_mpp(struct sk_buff *skb,
int path_idx = cb->args[2];
int err;
+ rtnl_lock();
err = nl80211_prepare_wdev_dump(skb, cb, &rdev, &wdev);
if (err)
- return err;
+ goto out_err;
if (!rdev->ops->dump_mpp) {
err = -EOPNOTSUPP;
@@ -5505,7 +5494,7 @@ static int nl80211_dump_mpp(struct sk_buff *skb,
cb->args[2] = path_idx;
err = skb->len;
out_err:
- nl80211_finish_wdev_dump(rdev);
+ rtnl_unlock();
return err;
}
@@ -7706,9 +7695,12 @@ static int nl80211_dump_scan(struct sk_buff *skb, struct netlink_callback *cb)
int start = cb->args[2], idx = 0;
int err;
+ rtnl_lock();
err = nl80211_prepare_wdev_dump(skb, cb, &rdev, &wdev);
- if (err)
+ if (err) {
+ rtnl_unlock();
return err;
+ }
wdev_lock(wdev);
spin_lock_bh(&rdev->bss_lock);
@@ -7731,7 +7723,7 @@ static int nl80211_dump_scan(struct sk_buff *skb, struct netlink_callback *cb)
wdev_unlock(wdev);
cb->args[2] = idx;
- nl80211_finish_wdev_dump(rdev);
+ rtnl_unlock();
return skb->len;
}
@@ -7816,9 +7808,10 @@ static int nl80211_dump_survey(struct sk_buff *skb, struct netlink_callback *cb)
int res;
bool radio_stats;
+ rtnl_lock();
res = nl80211_prepare_wdev_dump(skb, cb, &rdev, &wdev);
if (res)
- return res;
+ goto out_err;
/* prepare_wdev_dump parsed the attributes */
radio_stats = attrbuf[NL80211_ATTR_SURVEY_RADIO_STATS];
@@ -7859,7 +7852,7 @@ static int nl80211_dump_survey(struct sk_buff *skb, struct netlink_callback *cb)
cb->args[2] = survey_idx;
res = skb->len;
out_err:
- nl80211_finish_wdev_dump(rdev);
+ rtnl_unlock();
return res;
}
@@ -11661,17 +11654,13 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
void *data = NULL;
unsigned int data_len = 0;
- rtnl_lock();
-
if (cb->args[0]) {
/* subtract the 1 again here */
struct wiphy *wiphy = wiphy_idx_to_wiphy(cb->args[0] - 1);
struct wireless_dev *tmp;
- if (!wiphy) {
- err = -ENODEV;
- goto out_unlock;
- }
+ if (!wiphy)
+ return -ENODEV;
*rdev = wiphy_to_rdev(wiphy);
*wdev = NULL;
@@ -11691,23 +11680,19 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
attrbuf, nl80211_fam.maxattr, nl80211_policy);
if (err)
- goto out_unlock;
+ return err;
if (!attrbuf[NL80211_ATTR_VENDOR_ID] ||
- !attrbuf[NL80211_ATTR_VENDOR_SUBCMD]) {
- err = -EINVAL;
- goto out_unlock;
- }
+ !attrbuf[NL80211_ATTR_VENDOR_SUBCMD])
+ return -EINVAL;
*wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk), attrbuf);
if (IS_ERR(*wdev))
*wdev = NULL;
*rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk), attrbuf);
- if (IS_ERR(*rdev)) {
- err = PTR_ERR(*rdev);
- goto out_unlock;
- }
+ if (IS_ERR(*rdev))
+ return PTR_ERR(*rdev);
vid = nla_get_u32(attrbuf[NL80211_ATTR_VENDOR_ID]);
subcmd = nla_get_u32(attrbuf[NL80211_ATTR_VENDOR_SUBCMD]);
@@ -11720,19 +11705,15 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
if (vcmd->info.vendor_id != vid || vcmd->info.subcmd != subcmd)
continue;
- if (!vcmd->dumpit) {
- err = -EOPNOTSUPP;
- goto out_unlock;
- }
+ if (!vcmd->dumpit)
+ return -EOPNOTSUPP;
vcmd_idx = i;
break;
}
- if (vcmd_idx < 0) {
- err = -EOPNOTSUPP;
- goto out_unlock;
- }
+ if (vcmd_idx < 0)
+ return -EOPNOTSUPP;
if (attrbuf[NL80211_ATTR_VENDOR_DATA]) {
data = nla_data(attrbuf[NL80211_ATTR_VENDOR_DATA]);
@@ -11749,9 +11730,6 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
/* keep rtnl locked in successful case */
return 0;
- out_unlock:
- rtnl_unlock();
- return err;
}
static int nl80211_vendor_cmd_dump(struct sk_buff *skb,
@@ -11766,9 +11744,10 @@ static int nl80211_vendor_cmd_dump(struct sk_buff *skb,
int err;
struct nlattr *vendor_data;
+ rtnl_lock();
err = nl80211_prepare_vendor_dump(skb, cb, &rdev, &wdev);
if (err)
- return err;
+ goto out;
vcmd_idx = cb->args[2];
data = (void *)cb->args[3];
@@ -11777,15 +11756,21 @@ static int nl80211_vendor_cmd_dump(struct sk_buff *skb,
if (vcmd->flags & (WIPHY_VENDOR_CMD_NEED_WDEV |
WIPHY_VENDOR_CMD_NEED_NETDEV)) {
- if (!wdev)
- return -EINVAL;
+ if (!wdev) {
+ err = -EINVAL;
+ goto out;
+ }
if (vcmd->flags & WIPHY_VENDOR_CMD_NEED_NETDEV &&
- !wdev->netdev)
- return -EINVAL;
+ !wdev->netdev) {
+ err = -EINVAL;
+ goto out;
+ }
if (vcmd->flags & WIPHY_VENDOR_CMD_NEED_RUNNING) {
- if (!wdev_running(wdev))
- return -ENETDOWN;
+ if (!wdev_running(wdev)) {
+ err = -ENETDOWN;
+ goto out;
+ }
}
}
--
2.11.0
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