crypto: ccm - preserve the IV buffer

The IV buffer used during CCM operations is used twice, during both the
hashing step and the ciphering step.

When using a hardware accelerator that updates the contents of the IV
buffer at the end of ciphering operations, the value will be modified.
In the decryption case, the subsequent setup of the hashing algorithm
will interpret the updated IV instead of the original value, which can
lead to out-of-bounds writes.

Reuse the idata buffer, only used in the hashing step, to preserve the
IV's value during the ciphering step in the decryption case.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/ccm.c b/crypto/ccm.c
index 1ce37ae0ce565a130962f50244f331117fe965d8..0a083342ec8cf3b17c4da15c515c8c3d7a519a0f 100644 (file)
--- a/crypto/ccm.c
+++ b/crypto/ccm.c
@@ -363,7 +363,7 @@ static int crypto_ccm_decrypt(struct aead_request *req)
        unsigned int cryptlen = req->cryptlen;
        u8 *authtag = pctx->auth_tag;
        u8 *odata = pctx->odata;
-       u8 *iv = req->iv;
+       u8 *iv = pctx->idata;
        int err;
 
        cryptlen -= authsize;
@@ -379,6 +379,8 @@ static int crypto_ccm_decrypt(struct aead_request *req)
        if (req->src != req->dst)
                dst = pctx->dst;
 
+       memcpy(iv, req->iv, 16);
+
        skcipher_request_set_tfm(skreq, ctx->ctr);
        skcipher_request_set_callback(skreq, pctx->flags,
                                      crypto_ccm_decrypt_done, req);