[Kernel] Re: [PATCH OpenHarmony-5.10 05/18] tee: handle lookup of shm with reference count 0

在 2022/1/24 9:03, yiyuchangchun@126.com 写道:

From: Jens Wiklander

stable inclusion from stable-v5.10.89 commit c05d8f66ec3470e5212c4d08c46d6cb5738d600d issue: #I4RVJ4 CVE: CVE-2021-44733

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

Signed-off-by: Yu Changchun --------------------------------

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 Reviewed-by: Lars Persson Reviewed-by: Sumit Garg Reported-by: Patrik Lantz Signed-off-by: Jens Wiklander Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Signed-off-by: Zheng Zengkai Signed-off-by: Yu Changchun --- drivers/tee/tee_shm.c | 171 ++++++++++++++++------------------------ include/linux/tee_drv.h | 4 +- 2 files changed, 68 insertions(+), 107 deletions(-)

Reviewed-by: Wei Yongjun