diff options
author | Jens Wiklander <jens.wiklander@linaro.org> | 2021-12-09 17:59:37 +0300 |
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committer | Jens Wiklander <jens.wiklander@linaro.org> | 2021-12-16 11:30:14 +0300 |
commit | dfd0743f1d9ea76931510ed150334d571fbab49d (patch) | |
tree | 2db1935462851b541f55042896f7b2a52056105f /include | |
parent | d58071a8a76d779eedab38033ae4c821c30295a5 (diff) | |
download | linux-dfd0743f1d9ea76931510ed150334d571fbab49d.tar.xz |
tee: handle lookup of shm with reference count 0
Since the tee subsystem does not keep a strong reference to its idle
shared memory buffers, it races with other threads that try to destroy a
shared memory through a close of its dma-buf fd or by unmapping the
memory.
In tee_shm_get_from_id() when a lookup in teedev->idr has been
successful, it is possible that the tee_shm is in the dma-buf teardown
path, but that path is blocked by the teedev mutex. Since we don't have
an API to tell if the tee_shm is in the dma-buf teardown path or not we
must find another way of detecting this condition.
Fix this by doing the reference counting directly on the tee_shm using a
new refcount_t refcount field. dma-buf is replaced by using
anon_inode_getfd() instead, this separates the life-cycle of the
underlying file from the tee_shm. tee_shm_put() is updated to hold the
mutex when decreasing the refcount to 0 and then remove the tee_shm from
teedev->idr before releasing the mutex. This means that the tee_shm can
never be found unless it has a refcount larger than 0.
Fixes: 967c9cca2cc5 ("tee: generic TEE subsystem")
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Lars Persson <larper@axis.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reported-by: Patrik Lantz <patrik.lantz@axis.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/tee_drv.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h index a1f03461369b..cf5999626e28 100644 --- a/include/linux/tee_drv.h +++ b/include/linux/tee_drv.h @@ -195,7 +195,7 @@ int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method, * @offset: offset of buffer in user space * @pages: locked pages from userspace * @num_pages: number of locked pages - * @dmabuf: dmabuf used to for exporting to user space + * @refcount: reference counter * @flags: defined by TEE_SHM_* in tee_drv.h * @id: unique id of a shared memory object on this device, shared * with user space @@ -214,7 +214,7 @@ struct tee_shm { unsigned int offset; struct page **pages; size_t num_pages; - struct dma_buf *dmabuf; + refcount_t refcount; u32 flags; int id; u64 sec_world_id; |