crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()

[ Upstream commit a53ab94eb6850c3657392e2d2ce9b38c387a2633 ]

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.

Fixes: 3c4b23901a0c7 ("crypto: ecdh - Add ECDH software support")
Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

diff --git a/crypto/ecdh_helper.c b/crypto/ecdh_helper.c
index 66fcb2ea815445522ca9df6a94cfb8ddb7d919c4..fca63b559f655266fab1ff432dda85b21225c906 100644 (file)
--- 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))