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tee: amdtee: fix race condition in amdtee_open_session 

There is a potential race condition in amdtee_open_session that may
lead to use-after-free. For instance, in amdtee_open_session() after
sess->sess_mask is set, and before setting:

    sess->session_info[i] = session_info;

if amdtee_close_session() closes this same session, then 'sess' data
structure will be released, causing kernel panic when 'sess' is
accessed within amdtee_open_session().

The solution is to set the bit sess->sess_mask as the last step in
amdtee_open_session().

Fixes: 757cc3e9ff ("tee: add AMD-TEE driver")
Cc: stable@vger.kernel.org
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
This commit is contained in:
Rijo Thomas 2023-02-28 15:11:20 +05:30 committed by Jens Wiklander
parent c9c3395d5e
commit f8502fba45
1 changed files with 14 additions and 15 deletions
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29
drivers/tee/amdtee/core.c
View File

@ -267,35 +267,34 @@ int amdtee_open_session(struct tee_context *ctx,
goto out;
}
/* Open session with loaded TA */
handle_open_session(arg, &session_info, param);
if (arg->ret != TEEC_SUCCESS) {
pr_err("open_session failed %d\n", arg->ret);
handle_unload_ta(ta_handle);
kref_put(&sess->refcount, destroy_session);
goto out;
}
/* Find an empty session index for the given TA */
spin_lock(&sess->lock);
i = find_first_zero_bit(sess->sess_mask, TEE_NUM_SESSIONS);
if (i < TEE_NUM_SESSIONS)
if (i < TEE_NUM_SESSIONS) {
sess->session_info[i] = session_info;
set_session_id(ta_handle, i, &arg->session);
set_bit(i, sess->sess_mask);
}
spin_unlock(&sess->lock);
if (i >= TEE_NUM_SESSIONS) {
pr_err("reached maximum session count %d\n", TEE_NUM_SESSIONS);
handle_close_session(ta_handle, session_info);
handle_unload_ta(ta_handle);
kref_put(&sess->refcount, destroy_session);
rc = -ENOMEM;
goto out;
}
/* Open session with loaded TA */
handle_open_session(arg, &session_info, param);
if (arg->ret != TEEC_SUCCESS) {
pr_err("open_session failed %d\n", arg->ret);
spin_lock(&sess->lock);
clear_bit(i, sess->sess_mask);
spin_unlock(&sess->lock);
handle_unload_ta(ta_handle);
kref_put(&sess->refcount, destroy_session);
goto out;
}
sess->session_info[i] = session_info;
set_session_id(ta_handle, i, &arg->session);
out:
free_pages((u64)ta, get_order(ta_size));
return rc;