Commit a8348bca authored Nov 17, 2016 by Herbert Xu

crypto: algif_hash - Fix NULL hash crash with shash



Recently algif_hash has been changed to allow null hashes.  This
triggers a bug when used with an shash algorithm whereby it will
cause a crash during the digest operation.

This patch fixes it by avoiding the digest operation and instead
doing an init followed by a final which avoids the buggy code in
shash.

This patch also ensures that the result buffer is freed after an
error so that it is not returned as a genuine hash result on the
next recv call.

The shash/ahash wrapper code will be fixed later to handle this
case correctly.

Fixes: 493b2ed3 ("crypto: algif_hash - Handle NULL hashes correctly")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Laura Abbott <labbott@redhat.com>

parent a5a40d46

crypto/algif_hash.c

+10 −7

Original line number	Diff line number	Diff line
		@@ -214,23 +214,26 @@ static int hash_recvmsg(struct socket sock, struct msghdr msg, size_t len,

		ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);

		if (ctx->more) {
		if (!result) {
		err = af_alg_wait_for_completion(
		crypto_ahash_init(&ctx->req),
		&ctx->completion);
		if (err)
		goto unlock;
		}

		if (!result \|\| ctx->more) {
		ctx->more = 0;
		err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
		&ctx->completion);
		if (err)
		goto unlock;
		} else if (!result) {
		err = af_alg_wait_for_completion(
		crypto_ahash_digest(&ctx->req),
		&ctx->completion);
		}

		err = memcpy_to_msg(msg, ctx->result, len);

		hash_free_result(sk, ctx);

		unlock:
		hash_free_result(sk, ctx);
		release_sock(sk);

		return err ?: len;