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authorJann Horn <jannh@google.com>2018-04-04 21:03:21 +0200
committerJens Wiklander <jens.wiklander@linaro.org>2018-05-07 11:50:25 +0200
commitbb765d1c331f62b59049d35607ed2e365802bef9 (patch)
tree08178bf9dce45a1fd175e1a6cf65f58b91d6f0b8 /drivers/tee
parentLinux 4.17-rc4 (diff)
downloadlinux-bb765d1c331f62b59049d35607ed2e365802bef9.tar.xz
linux-bb765d1c331f62b59049d35607ed2e365802bef9.zip
tee: shm: fix use-after-free via temporarily dropped reference
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>
Diffstat (limited to 'drivers/tee')
-rw-r--r--drivers/tee/tee_shm.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 556960a1bab3..07d3be6f0780 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -360,9 +360,10 @@ int tee_shm_get_fd(struct tee_shm *shm)
if (!(shm->flags & TEE_SHM_DMA_BUF))
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;
}