crypto: starfive - Correctly handle return of sg_nents_for_len

The return value of sg_nents_for_len was assigned to an unsigned long
in starfive_hash_digest, causing negative error codes to be converted
to large positive integers.

Add error checking for sg_nents_for_len and return immediately on
failure to prevent potential buffer overflows.

Fixes: 7883d1b28a2b ("crypto: starfive - Add hash and HMAC support")
Signed-off-by: Haotian Zhang <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/starfive/jh7110-hash.c

···
 	struct starfive_cryp_ctx *ctx = crypto_ahash_ctx(tfm);
 	struct starfive_cryp_request_ctx *rctx = ahash_request_ctx(req);
 	struct starfive_cryp_dev *cryp = ctx->cryp;
+	int sg_len;
 
 	memset(rctx, 0, sizeof(struct starfive_cryp_request_ctx));
 
···
 	rctx->in_sg = req->src;
 	rctx->blksize = crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
 	rctx->digsize = crypto_ahash_digestsize(tfm);
-	rctx->in_sg_len = sg_nents_for_len(rctx->in_sg, rctx->total);
+	sg_len = sg_nents_for_len(rctx->in_sg, rctx->total);
+	if (sg_len < 0)
+		return sg_len;
+	rctx->in_sg_len = sg_len;
 	ctx->rctx = rctx;
 
 	return crypto_transfer_hash_request_to_engine(cryp->engine, req);