linux-kernel - [PATCH] crypto: ecdh_helper - Ensure 'len >= secret.len' in decode

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Date:   Wed,  3 Feb 2021 11:28:37 +0000
From:   Daniele Alessandrelli <daniele.alessandrelli@...ux.intel.com>
To:     herbert@...dor.apana.org.au
Cc:     daniele.alessandrelli@...el.com, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()

From: Daniele Alessandrelli <daniele.alessandrelli@...el.com>

The length ('len' parameter) passed to crypto_ecdh_decode_key() is never
checked against the length encoded in the passed buffer ('buf'
parameter). This could lead to an out-of-bounds access when the passed
length is less than the encoded length.

Add a check to prevent that.

Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@...el.com>
---
 crypto/ecdh_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/ecdh_helper.c b/crypto/ecdh_helper.c
index 66fcb2ea8154..fca63b559f65 100644
--- a/crypto/ecdh_helper.c
+++ b/crypto/ecdh_helper.c
@@ -67,6 +67,9 @@ int crypto_ecdh_decode_key(const char *buf, unsigned int len,
 	if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
 		return -EINVAL;
 
+	if (unlikely(len < secret.len))
+		return -EINVAL;
+
 	ptr = ecdh_unpack_data(&params->curve_id, ptr, sizeof(params->curve_id));
 	ptr = ecdh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
 	if (secret.len != crypto_ecdh_key_len(params))
-- 
2.26.2