diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2013-06-19 10:09:57 +0200 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2013-06-19 18:31:20 +0200 |
| commit | 3a5a423bb958ad22eeccca66c533e85bf69ba10e (patch) | |
| tree | ee184cabce960d6ceaf1d2ac4efd0f406c9b5555 /net/wireless/nl80211.c | |
| parent | 795d855d56c6d172f50a974f603ba923ac93ee76 (diff) | |
| download | lwn-3a5a423bb958ad22eeccca66c533e85bf69ba10e.tar.gz lwn-3a5a423bb958ad22eeccca66c533e85bf69ba10e.zip | |
nl80211: fix attrbuf access race by allocating a separate one
Since my commit 3713b4e364 ("nl80211: allow splitting wiphy
information in dumps"), nl80211_dump_wiphy() uses the global
nl80211_fam.attrbuf for parsing the incoming data. This wouldn't
be a problem if it only did so on the first dump iteration which
is locked against other commands in generic netlink, but due to
space constraints in cb->args (the needed state doesn't fit) I
decided to always parse the original message. That's racy though
since nl80211_fam.attrbuf could be used by some other parsing in
generic netlink concurrently.
For now, fix this by allocating a separate parse buffer (it's a
bit too big for the stack, currently 1448 bytes on 64-bit). For
-next, I'll change the code to parse into the global buffer in
the first round only and then allocate a smaller buffer to keep
the data in cb->args.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/wireless/nl80211.c')
| -rw-r--r-- | net/wireless/nl80211.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index d5aed3bb3945..b14b7e3cb6e6 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -1564,12 +1564,17 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb) struct cfg80211_registered_device *dev; s64 filter_wiphy = -1; bool split = false; - struct nlattr **tb = nl80211_fam.attrbuf; + struct nlattr **tb; int res; + /* will be zeroed in nlmsg_parse() */ + tb = kmalloc(sizeof(*tb) * (NL80211_ATTR_MAX + 1), GFP_KERNEL); + if (!tb) + return -ENOMEM; + mutex_lock(&cfg80211_mutex); res = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize, - tb, nl80211_fam.maxattr, nl80211_policy); + tb, NL80211_ATTR_MAX, nl80211_policy); if (res == 0) { split = tb[NL80211_ATTR_SPLIT_WIPHY_DUMP]; if (tb[NL80211_ATTR_WIPHY]) @@ -1583,6 +1588,7 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb) netdev = dev_get_by_index(sock_net(skb->sk), ifidx); if (!netdev) { mutex_unlock(&cfg80211_mutex); + kfree(tb); return -ENODEV; } if (netdev->ieee80211_ptr) { @@ -1593,6 +1599,7 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb) dev_put(netdev); } } + kfree(tb); list_for_each_entry(dev, &cfg80211_rdev_list, list) { if (!net_eq(wiphy_net(&dev->wiphy), sock_net(skb->sk))) |