diff options
author | Jens Wiklander <jens.wiklander@linaro.org> | 2021-12-09 15:59:37 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-05 12:37:43 +0100 |
commit | 940e68e57ab69248fabba5889e615305789db8a7 (patch) | |
tree | 3be309a02bc87cf330e4e234b6b7fefb72e9632b /include/linux | |
parent | 4b38b12092b4d75d994dbacf8bd77a494a2a1b8a (diff) |
tee: handle lookup of shm with reference count 0
commit dfd0743f1d9ea76931510ed150334d571fbab49d upstream.
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>
[JW: backport to 5.4-stable]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
-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 cd15c1b7fae0..e08ace76eba6 100644 --- a/include/linux/tee_drv.h +++ b/include/linux/tee_drv.h @@ -178,7 +178,7 @@ void tee_device_unregister(struct tee_device *teedev); * @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 * @@ -195,7 +195,7 @@ struct tee_shm { unsigned int offset; struct page **pages; size_t num_pages; - struct dma_buf *dmabuf; + refcount_t refcount; u32 flags; int id; }; |