bbdd4a5162
commit dfb703ad2a8d366b829818a558337be779746575 upstream.
dma-buf backed shared memory cannot be reliably freed and unregistered
during a kexec operation even when tee_shm_free() is called on the shm
from a .shutdown hook. The problem occurs because dma_buf_put() calls
fput() which then uses task_work_add(), with the TWA_RESUME parameter,
to queue tee_shm_release() to be called before the current task returns
to user mode. However, the current task never returns to user mode
before the kexec completes so the memory is never freed nor
unregistered.
Use tee_shm_alloc_kernel_buf() to avoid dma-buf backed shared memory
allocation so that tee_shm_free() can directly call tee_shm_release().
This will ensure that the shm can be freed and unregistered during a
kexec operation.
Fixes: 09e574831b27 ("tpm/tpm_ftpm_tee: A driver for firmware TPM running inside TEE")
Fixes: 1760eb689ed6 ("tpm/tpm_ftpm_tee: add shutdown call back")
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.