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Date:   Thu, 27 Feb 2020 19:19:54 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Jens Wiklander <jens.wiklander@linaro.org>,
        Rijo Thomas <Rijo-john.Thomas@amd.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>,
        tee-dev@lists.linaro.org, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org
Subject: [PATCH] tee: amdtee: out of bounds read in find_session()
Message-ID: <20200227161954.fo7pbbgomdjkraxq@kili.mountain>
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The "index" is a user provided value from 0-USHRT_MAX.  If it's over
TEE_NUM_SESSIONS (31) then it results in an out of bounds read when we
call test_bit(index, sess->sess_mask).

Fixes: 757cc3e9ff1d ("tee: add AMD-TEE driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/tee/amdtee/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tee/amdtee/core.c b/drivers/tee/amdtee/core.c
index 6370bb55f512..dbc238c7c263 100644
--- a/drivers/tee/amdtee/core.c
+++ b/drivers/tee/amdtee/core.c
@@ -139,6 +139,9 @@ static struct amdtee_session *find_session(struct amdtee_context_data *ctxdata,
 	u32 index = get_session_index(session);
 	struct amdtee_session *sess;
 
+	if (index >= TEE_NUM_SESSIONS)
+		return NULL;
+
 	list_for_each_entry(sess, &ctxdata->sess_list, list_node)
 		if (ta_handle == sess->ta_handle &&
 		    test_bit(index, sess->sess_mask))
-- 
2.11.0