tree 04e1bc509bbb1dd5323c29df0c642a5cdbec161e
parent 7098296a362a96051fa120abf48f0095818b99cd
author Dmitry Vyukov <dvyukov@google.com> 1442503029 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1443981820 +0100

tty: fix data race in tty_buffer_flush

tty_buffer_flush frees not acquired buffers.
As the result, for example, read of b->size in tty_buffer_free
can return garbage value which will lead to a huge buffer
hanging in the freelist. This is just the benignest
manifestation of freeing of a not acquired object.
If the object is passed to kfree, heap can be corrupted.

Acquire visibility over the buffer before freeing it.

The data race was found with KernelThreadSanitizer (KTSAN).

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>