• Jens Wiklander's avatar
    optee: immediately free RPC buffers that are released by OP-TEE · 5d2d5365
    Jens Wiklander authored
    This commit fixes a case overlooked in [1].
    
    There are two kinds of shared memory buffers used by OP-TEE:
    1. Normal payload buffer
    2. Internal command structure buffers
    
    The internal command structure buffers are represented with a shadow
    copy internally in Xen since this buffer can contain physical addresses
    that may need to be translated between real physical address and guest
    physical address without leaking information to the guest.
    
    [1] fixes the problem when releasing the normal payload buffers. The
    internal command structure buffers must be released in the same way.
    Failure to follow this order opens a window where the guest has freed
    the shared memory but Xen is still tracking the buffer.
    
    During this window the guest may happen to recycle this particular
    shared memory in some other thread and try to use it. Xen will block
    this which will lead to spurious failures to register a new shared
    memory block.
    
    Fix this by freeing the internal command structure buffers first before
    informing the guest that the buffer can be freed.
    
    [1] 5b13eb1d ("optee: immediately free buffers that are released by OP-TEE")
    Signed-off-by: default avatarJens Wiklander <jens.wiklander@linaro.org>
    Reviewed-by: default avatarVolodymyr Babchuk <volodymyr_babchuk@epam.com>
    [stefano: minor code style fix]
    Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@xilinx.com>
    5d2d5365
optee.c 52.7 KB