diff options
author | Pawel Wieczorkiewicz <wipawel@amazon.de> | 2020-12-14 10:25:57 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-30 11:51:46 +0100 |
commit | 8f3f6de44f7cc93a4723e63ea4381332826a6790 (patch) | |
tree | a97ef62bff8f4945ec41fedbb73dbdfb32bff9d3 /include/xen | |
parent | 383c60c16dd8a44800717e19418f98d5e6a3ad4c (diff) |
xen-blkback: set ring->xenblkd to NULL after kthread_stop()
commit 1c728719a4da6e654afb9cc047164755072ed7c9 upstream.
When xen_blkif_disconnect() is called, the kernel thread behind the
block interface is stopped by calling kthread_stop(ring->xenblkd).
The ring->xenblkd thread pointer being non-NULL determines if the
thread has been already stopped.
Normally, the thread's function xen_blkif_schedule() sets the
ring->xenblkd to NULL, when the thread's main loop ends.
However, when the thread has not been started yet (i.e.
wake_up_process() has not been called on it), the xen_blkif_schedule()
function would not be called yet.
In such case the kthread_stop() call returns -EINTR and the
ring->xenblkd remains dangling.
When this happens, any consecutive call to xen_blkif_disconnect (for
example in frontend_changed() callback) leads to a kernel crash in
kthread_stop() (e.g. NULL pointer dereference in exit_creds()).
This is XSA-350.
Cc: <stable@vger.kernel.org> # 4.12
Fixes: a24fa22ce22a ("xen/blkback: don't use xen_blkif_get() in xen-blkback kthread")
Reported-by: Olivier Benjamin <oliben@amazon.com>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/xen')
0 files changed, 0 insertions, 0 deletions