tee: amdtee: fix use-after-free vulnerability in amdtee_close_session
commit f4384b3e54ea813868bb81a861bf5b2406e15d8f upstream.
There is a potential race condition in amdtee_close_session that may
cause use-after-free in amdtee_open_session. For instance, if a session
has refcount == 1, and one thread tries to free this session via:
kref_put(&sess->refcount, destroy_session);
the reference count will get decremented, and the next step would be to
call destroy_session(). However, if in another thread,
amdtee_open_session() is called before destroy_session() has completed
execution, alloc_session() may return 'sess' that will be freed up
later in destroy_session() leading to use-after-free in
amdtee_open_session.
To fix this issue, treat decrement of sess->refcount and removal of
'sess' from session list in destroy_session() as a critical section, so
that it is executed atomically.
Fixes: 757cc3e9ff
("tee: add AMD-TEE driver")
Cc: stable@vger.kernel.org
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
0ea0231dd1
commit
da7ce52a2f
@ -217,12 +217,12 @@ static int copy_ta_binary(struct tee_context *ctx, void *ptr, void **ta,
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return rc;
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}
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/* mutex must be held by caller */
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static void destroy_session(struct kref *ref)
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{
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struct amdtee_session *sess = container_of(ref, struct amdtee_session,
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refcount);
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mutex_lock(&session_list_mutex);
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list_del(&sess->list_node);
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mutex_unlock(&session_list_mutex);
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kfree(sess);
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@ -272,7 +272,8 @@ int amdtee_open_session(struct tee_context *ctx,
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if (arg->ret != TEEC_SUCCESS) {
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pr_err("open_session failed %d\n", arg->ret);
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handle_unload_ta(ta_handle);
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kref_put(&sess->refcount, destroy_session);
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kref_put_mutex(&sess->refcount, destroy_session,
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&session_list_mutex);
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goto out;
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}
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@ -290,7 +291,8 @@ int amdtee_open_session(struct tee_context *ctx,
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pr_err("reached maximum session count %d\n", TEE_NUM_SESSIONS);
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handle_close_session(ta_handle, session_info);
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handle_unload_ta(ta_handle);
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kref_put(&sess->refcount, destroy_session);
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kref_put_mutex(&sess->refcount, destroy_session,
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&session_list_mutex);
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rc = -ENOMEM;
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goto out;
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}
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@ -331,7 +333,7 @@ int amdtee_close_session(struct tee_context *ctx, u32 session)
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handle_close_session(ta_handle, session_info);
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handle_unload_ta(ta_handle);
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kref_put(&sess->refcount, destroy_session);
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kref_put_mutex(&sess->refcount, destroy_session, &session_list_mutex);
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return 0;
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}
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