linux-sg2042/net/netlink
Al Viro 24dff96a37 fix misuses of f_count() in ppp and netlink
we used to check for "nobody else could start doing anything with
that opened file" by checking that refcount was 2 or less - one
for descriptor table and one we'd acquired in fget() on the way to
wherever we are.  That was race-prone (somebody else might have
had a reference to descriptor table and do fget() just as we'd
been checking) and it had become flat-out incorrect back when
we switched to fget_light() on those codepaths - unlike fget(),
it doesn't grab an extra reference unless the descriptor table
is shared.  The same change allowed a race-free check, though -
we are safe exactly when refcount is less than 2.

It was a long time ago; pre-2.6.12 for ioctl() (the codepath leading
to ppp one) and 2.6.17 for sendmsg() (netlink one).  OTOH,
netlink hadn't grown that check until 3.9 and ppp used to live
in drivers/net, not drivers/net/ppp until 3.1.  The bug existed
well before that, though, and the same fix used to apply in old
location of file.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-09 02:39:17 -04:00
..
Kconfig netlink: kconfig: move mmap i/o into netlink kconfig 2013-05-01 15:02:42 -04:00
Makefile netlink: Diag core and basic socket info dumping (v2) 2013-03-21 12:38:03 -04:00
af_netlink.c fix misuses of f_count() in ppp and netlink 2014-10-09 02:39:17 -04:00
af_netlink.h netlink: hold nl_sock_hash_lock during diag dump 2014-08-06 19:17:44 -07:00
diag.c netlink: hold nl_sock_hash_lock during diag dump 2014-08-06 19:17:44 -07:00
genetlink.c genetlink: remove superfluous assignment 2014-06-02 10:36:18 -07:00