4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jann Horn jannh@google.com
commit bb765d1c331f62b59049d35607ed2e365802bef9 upstream.
Bump the file's refcount before moving the reference into the fd table, not afterwards. The old code could drop the file's refcount to zero for a short moment before calling get_file() via get_dma_buf().
This code can only be triggered on ARM systems that use Linaro's OP-TEE.
Fixes: 967c9cca2cc5 ("tee: generic TEE subsystem") Signed-off-by: Jann Horn jannh@google.com Signed-off-by: Jens Wiklander jens.wiklander@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tee/tee_shm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -203,9 +203,10 @@ int tee_shm_get_fd(struct tee_shm *shm) if ((shm->flags & req_flags) != req_flags) return -EINVAL;
+ get_dma_buf(shm->dmabuf); fd = dma_buf_fd(shm->dmabuf, O_CLOEXEC); - if (fd >= 0) - get_dma_buf(shm->dmabuf); + if (fd < 0) + dma_buf_put(shm->dmabuf); return fd; }