nl80211: clear skb cb before passing to netlink
In testmode and vendor command reply/event SKBs we use the
skb cb data to store nl80211 parameters between allocation
and sending. This causes the code for CONFIG_NETLINK_MMAP
to get confused, because it takes ownership of the skb cb
data when the SKB is handed off to netlink, and it doesn't
explicitly clear it.
Clear the skb cb explicitly when we're done and before it
gets passed to netlink to avoid this issue.
Cc: stable@vger.kernel.org [this goes way back]
Reported-by: Assaf Azulay <assaf.azulay@intel.com>
Reported-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index df7b133..7257164 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -6969,6 +6969,9 @@
struct nlattr *data = ((void **)skb->cb)[2];
enum nl80211_multicast_groups mcgrp = NL80211_MCGRP_TESTMODE;
+ /* clear CB data for netlink core to own from now on */
+ memset(skb->cb, 0, sizeof(skb->cb));
+
nla_nest_end(skb, data);
genlmsg_end(skb, hdr);
@@ -9294,6 +9297,9 @@
void *hdr = ((void **)skb->cb)[1];
struct nlattr *data = ((void **)skb->cb)[2];
+ /* clear CB data for netlink core to own from now on */
+ memset(skb->cb, 0, sizeof(skb->cb));
+
if (WARN_ON(!rdev->cur_cmd_info)) {
kfree_skb(skb);
return -EINVAL;
