IB/umad: Fix use-after-free on close
authorBart Van Assche <bvanassche@acm.org>
Fri, 6 Jun 2014 16:25:04 +0000 (18:25 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 7 Jul 2014 01:54:14 +0000 (18:54 -0700)
commit30f5a010a9d507ac6f4e70a5b5ae139269c300ac
tree10442abfbd1ccd6c016fae736f5b30d7c24ee594
parentf6a9f42bf2f1dbcb3f6be2805af2fde96d422298
IB/umad: Fix use-after-free on close

commit 60e1751cb52cc6d1ae04b6bd3c2b96e770b5823f upstream.

Avoid that closing /dev/infiniband/umad<n> or /dev/infiniband/issm<n>
triggers a use-after-free.  __fput() invokes f_op->release() before it
invokes cdev_put().  Make sure that the ib_umad_device structure is
freed by the cdev_put() call instead of f_op->release().  This avoids
that changing the port mode from IB into Ethernet and back to IB
followed by restarting opensmd triggers the following kernel oops:

    general protection fault: 0000 [#1] PREEMPT SMP
    RIP: 0010:[<ffffffff810cc65c>]  [<ffffffff810cc65c>] module_put+0x2c/0x170
    Call Trace:
     [<ffffffff81190f20>] cdev_put+0x20/0x30
     [<ffffffff8118e2ce>] __fput+0x1ae/0x1f0
     [<ffffffff8118e35e>] ____fput+0xe/0x10
     [<ffffffff810723bc>] task_work_run+0xac/0xe0
     [<ffffffff81002a9f>] do_notify_resume+0x9f/0xc0
     [<ffffffff814b8398>] int_signal+0x12/0x17

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=75051
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/infiniband/core/user_mad.c