Commit 0db5bc85 authored by Daniele Alessandrelli's avatar Daniele Alessandrelli Committed by Herbert Xu
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crypto: keembay-ocs-aes - Fix 'q' assignment during CCM B0 generation 

In ocs_aes_ccm_write_b0(), 'q' (the octet length of the binary
representation of the octet length of the payload) is set to 'iv[0]',
while it should be set to 'iv[0] & 0x7' (i.e., only the last 3
bits of iv[0] should be used), as documented in NIST Special Publication
800-38C:
https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38c.pdf



In practice, this is not an issue, since 'iv[0]' is checked to be in the
range [1-7] by ocs_aes_validate_inputs(), but let's fix the assignment
anyway, in order to make the code more robust.

Signed-off-by: default avatarDaniele Alessandrelli <daniele.alessandrelli@intel.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent cfb28fde

drivers/crypto/keembay/ocs-aes.c

+3 −3
Original line number Diff line number Diff line
@@ -1080,15 +1080,15 @@ static int ocs_aes_ccm_write_b0(const struct ocs_aes_dev *aes_dev, 
	/*

	 * q is the octet length of Q.

	 * q can only be an element of {2, 3, 4, 5, 6, 7, 8} and is encoded as

	 * q - 1 == iv[0]

	 * q - 1 == iv[0] & 0x7;

	 */

	b0[0] |= iv[0] & 0x7;

	/*

	 * Copy the Nonce N from IV to B0; N is located in iv[1]..iv[15 - q]

	 * and must be copied to b0[1]..b0[15-q].

	 * q == iv[0] + 1

	 * q == (iv[0] & 0x7) + 1

	 */

	q = iv[0] + 1;

	q = (iv[0] & 0x7) + 1;

	for (i = 1; i <= 15 - q; i++)

		b0[i] = iv[i];

	/*