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authorJohannes Berg <johannes.berg@intel.com>2013-06-19 08:09:57 (GMT)
committerJohannes Berg <johannes.berg@intel.com>2013-06-19 16:31:20 (GMT)
commit3a5a423bb958ad22eeccca66c533e85bf69ba10e (patch)
treeee184cabce960d6ceaf1d2ac4efd0f406c9b5555 /net
parent795d855d56c6d172f50a974f603ba923ac93ee76 (diff)
downloadlinux-3a5a423bb958ad22eeccca66c533e85bf69ba10e.tar.xz
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')
-rw-r--r--net/wireless/nl80211.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d5aed3b..b14b7e3 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)))