static int crypto_cbcmac_digest_update(struct shash_desc *pdesc, const u8 *p,
				       unsigned int len)
{
	struct crypto_shash *parent = pdesc->tfm;
	struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	struct crypto_cipher *tfm = tctx->child;
	int bs = crypto_shash_digestsize(parent);
	u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;

	while (len > 0) {
		unsigned int l = min(len, bs - ctx->len);

		crypto_xor(dg + ctx->len, p, l);
		ctx->len +=l;
		len -= l;
		p += l;

		if (ctx->len == bs) {
			crypto_cipher_encrypt_one(tfm, dg, dg);
			ctx->len = 0;
		}
	}

	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.