linux/net/netlink
David Herrmann 47191d65b6 netlink: fix locking around NETLINK_LIST_MEMBERSHIPS
Currently, NETLINK_LIST_MEMBERSHIPS grabs the netlink table while copying
the membership state to user-space. However, grabing the netlink table is
effectively a write_lock_irq(), and as such we should not be triggering
page-faults in the critical section.

This can be easily reproduced by the following snippet:
    int s = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    void *p = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
    int r = getsockopt(s, 0x10e, 9, p, (void*)((char*)p + 4092));

This should work just fine, but currently triggers EFAULT and a possible
WARN_ON below handle_mm_fault().

Fix this by reducing locking of NETLINK_LIST_MEMBERSHIPS to a read-side
lock. The write-lock was overkill in the first place, and the read-lock
allows page-faults just fine.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-22 07:18:28 -07:00
..
af_netlink.c netlink: fix locking around NETLINK_LIST_MEMBERSHIPS 2015-10-22 07:18:28 -07:00
af_netlink.h netlink: Replace rhash_portid with bound 2015-09-24 12:07:08 -07:00
diag.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
genetlink.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-01-27 16:59:56 -08:00
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