4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jann Horn <jannh@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
