From ea90e0dc8cecba6359b481e24d9c37160f6f524f Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 15 Mar 2017 14:26:04 +0100 Subject: [PATCH] nl80211: fix dumpit error path RTNL deadlocks 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. Cc: stable@vger.kernel.org Reported-by: Sowmini Varadhan Reported-by: Dmitry Vyukov Signed-off-by: Johannes Berg --- 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 d7f8be4e321a..2312dc2ffdb9 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; } @@ -7674,9 +7663,12 @@ 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); @@ -7699,7 +7691,7 @@ 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; } @@ -7784,9 +7776,10 @@ 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]; @@ -7827,7 +7820,7 @@ 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; } @@ -11508,17 +11501,13 @@ 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; @@ -11538,23 +11527,19 @@ 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]); @@ -11567,19 +11552,15 @@ 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]); @@ -11596,9 +11577,6 @@ 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, @@ -11613,9 +11591,10 @@ 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]; @@ -11624,15 +11603,21 @@ 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; + } } } -- 2.20.1