static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
{
	const char *constants;

	ctx->input[1] = U8TO32_LITTLE(k + 0);
	ctx->input[2] = U8TO32_LITTLE(k + 4);
	ctx->input[3] = U8TO32_LITTLE(k + 8);
	ctx->input[4] = U8TO32_LITTLE(k + 12);
	if (kbytes == 32) { /* recommended */
		k += 16;
		constants = sigma;
	} else { /* kbytes == 16 */
		constants = tau;
	}
	ctx->input[11] = U8TO32_LITTLE(k + 0);
	ctx->input[12] = U8TO32_LITTLE(k + 4);
	ctx->input[13] = U8TO32_LITTLE(k + 8);
	ctx->input[14] = U8TO32_LITTLE(k + 12);
	ctx->input[0] = U8TO32_LITTLE(constants + 0);
	ctx->input[5] = U8TO32_LITTLE(constants + 4);
	ctx->input[10] = U8TO32_LITTLE(constants + 8);
	ctx->input[15] = U8TO32_LITTLE(constants + 12);
}

This category addresses vulnerabilities caused by flawed access control mechanisms, where incorrect permission settings allow unauthorized users to access restricted resources.