nl80211: fix attrbuf access race by allocating a separate one
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 <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Acked-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>
Acked-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>
Signed-off-by: Johannes Berg <bff32994ff0f8d048f262a8388145a71b6071bfe@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas