This is a note to let you know that I've just added the patch titled nl80211: fix dumpit error path RTNL deadlocks to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nl80211-fix-dumpit-error-path-rtnl-deadlocks.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ea90e0dc8cecba6359b481e24d9c37160f6f524f Mon Sep 17 00:00:00 2001 From: Johannes Berg <johannes.berg@xxxxxxxxx> Date: Wed, 15 Mar 2017 14:26:04 +0100 Subject: nl80211: fix dumpit error path RTNL deadlocks From: Johannes Berg <johannes.berg@xxxxxxxxx> commit ea90e0dc8cecba6359b481e24d9c37160f6f524f upstream. 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@xxxxxxxxxx> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/wireless/nl80211.c | 133 ++++++++++++++++++++++--------------------------- 1 file changed, 60 insertions(+), 73 deletions(-) --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -548,21 +548,17 @@ static int nl80211_prepare_wdev_dump(str { int err; - rtnl_lock(); - if (!cb->args[0]) { err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize, nl80211_fam.attrbuf, nl80211_fam.maxattr, nl80211_policy); if (err) - goto out_unlock; + return err; *wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk), nl80211_fam.attrbuf); - 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; @@ -572,10 +568,8 @@ static int nl80211_prepare_wdev_dump(str 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; @@ -586,21 +580,11 @@ static int nl80211_prepare_wdev_dump(str } } - 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 */ @@ -2584,17 +2568,17 @@ static int nl80211_dump_interface(struct 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; @@ -2639,12 +2623,14 @@ static int nl80211_dump_interface(struct 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) @@ -4371,9 +4357,10 @@ static int nl80211_dump_station(struct s 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; @@ -4408,7 +4395,7 @@ static int nl80211_dump_station(struct s cb->args[2] = sta_idx; err = skb->len; out_err: - nl80211_finish_wdev_dump(rdev); + rtnl_unlock(); return err; } @@ -5179,9 +5166,10 @@ static int nl80211_dump_mpath(struct sk_ 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; @@ -5214,7 +5202,7 @@ static int nl80211_dump_mpath(struct sk_ cb->args[2] = path_idx; err = skb->len; out_err: - nl80211_finish_wdev_dump(rdev); + rtnl_unlock(); return err; } @@ -5374,9 +5362,10 @@ static int nl80211_dump_mpp(struct sk_bu 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; @@ -5409,7 +5398,7 @@ static int nl80211_dump_mpp(struct sk_bu cb->args[2] = path_idx; err = skb->len; out_err: - nl80211_finish_wdev_dump(rdev); + rtnl_unlock(); return err; } @@ -7556,9 +7545,12 @@ static int nl80211_dump_scan(struct sk_b 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); @@ -7581,7 +7573,7 @@ static int nl80211_dump_scan(struct sk_b wdev_unlock(wdev); cb->args[2] = idx; - nl80211_finish_wdev_dump(rdev); + rtnl_unlock(); return skb->len; } @@ -7665,9 +7657,10 @@ static int nl80211_dump_survey(struct sk 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 = nl80211_fam.attrbuf[NL80211_ATTR_SURVEY_RADIO_STATS]; @@ -7708,7 +7701,7 @@ static int nl80211_dump_survey(struct sk cb->args[2] = survey_idx; res = skb->len; out_err: - nl80211_finish_wdev_dump(rdev); + rtnl_unlock(); return res; } @@ -11299,17 +11292,13 @@ static int nl80211_prepare_vendor_dump(s 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; @@ -11330,13 +11319,11 @@ static int nl80211_prepare_vendor_dump(s nl80211_fam.attrbuf, nl80211_fam.maxattr, nl80211_policy); if (err) - goto out_unlock; + return err; if (!nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_ID] || - !nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_SUBCMD]) { - err = -EINVAL; - goto out_unlock; - } + !nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_SUBCMD]) + return -EINVAL; *wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk), nl80211_fam.attrbuf); @@ -11345,10 +11332,8 @@ static int nl80211_prepare_vendor_dump(s *rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk), nl80211_fam.attrbuf); - if (IS_ERR(*rdev)) { - err = PTR_ERR(*rdev); - goto out_unlock; - } + if (IS_ERR(*rdev)) + return PTR_ERR(*rdev); vid = nla_get_u32(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_ID]); subcmd = nla_get_u32(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_SUBCMD]); @@ -11361,19 +11346,15 @@ static int nl80211_prepare_vendor_dump(s 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 (nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_DATA]) { data = nla_data(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_DATA]); @@ -11390,9 +11371,6 @@ static int nl80211_prepare_vendor_dump(s /* keep rtnl locked in successful case */ return 0; - out_unlock: - rtnl_unlock(); - return err; } static int nl80211_vendor_cmd_dump(struct sk_buff *skb, @@ -11407,9 +11385,10 @@ static int nl80211_vendor_cmd_dump(struc 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]; @@ -11418,18 +11397,26 @@ static int nl80211_vendor_cmd_dump(struc 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->netdev && - !netif_running(wdev->netdev)) - return -ENETDOWN; - if (!wdev->netdev && !wdev->p2p_started) - return -ENETDOWN; + !netif_running(wdev->netdev)) { + err = -ENETDOWN; + goto out; + } + if (!wdev->netdev && !wdev->p2p_started) { + err = -ENETDOWN; + goto out; + } } } Patches currently in stable-queue which might be from johannes.berg@xxxxxxxxx are queue-4.9/nl80211-fix-dumpit-error-path-rtnl-deadlocks.patch