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authorJens Wiklander <jens.wiklander@linaro.org>2021-12-09 17:59:37 +0300
committerJens Wiklander <jens.wiklander@linaro.org>2021-12-16 11:30:14 +0300
commitdfd0743f1d9ea76931510ed150334d571fbab49d (patch)
tree2db1935462851b541f55042896f7b2a52056105f /include
parentd58071a8a76d779eedab38033ae4c821c30295a5 (diff)
downloadlinux-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.h4
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;