tee: shm: fix use-after-free via temporarily dropped reference
commitpull/10/headbb765d1c33
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:967c9cca2c
("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>
parent
9a19a93bdd
commit
bca7faea54
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@ -203,9 +203,10 @@ int tee_shm_get_fd(struct tee_shm *shm)
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if ((shm->flags & req_flags) != req_flags)
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return -EINVAL;
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get_dma_buf(shm->dmabuf);
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fd = dma_buf_fd(shm->dmabuf, O_CLOEXEC);
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if (fd >= 0)
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get_dma_buf(shm->dmabuf);
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if (fd < 0)
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dma_buf_put(shm->dmabuf);
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return fd;
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}
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