There are two common ways for x86 compilers to indicate that execution should not have reached a particular point: One is the single-byte int 3 breakpoint opcode. And the other is the two-byte ud2 invalid instruction opcode. How do they decide which one to use?

The two types of “bad instructions” are typically for different purposes.

The int 3 means “There is no code here. If you somehow got here, then somebody used an invalid function pointer.” It is used as padding, such as between functions. There is no way that code can reach the int 3 by normal execution. You must have generated an invalid address and called it.

The ud2 is used to mark the case when execution reached something that should be unreachable. It means “You executed a code path that the standard says is undefined behavior.” For example, falling off the end of a non-void function without returning a value, or following the call to a [[noreturn]] function in case it somehow managed to return.

Using int 3 for “there is not even code here” is important because it’s a one-byte instruction. If you had used the two-byte instruction ud2 instruction, then that stray function pointer might land on the second byte of the instruction, in which case it’s not ud2 any more. Instead of stopping immediately, it starts executing garbage code:

0b 0f            or      ecx,dword ptr [edi]
0b 0f            or      ecx,dword ptr [edi]
0b 0f            or      ecx,dword ptr [edi]

Okay, so what does this mean for you?

If you find yourself executing the ud2 instruction, then look for logic flaws in your code. If you find yourself executing the int 3 instruction, then look for an uninitialized function pointer variable, or a hard-coded breakpoint, or a debugger-inserted breakpoint.

The post Why does the compiler sometimes use <CODE>ud2</CODE> and sometimes <CODE>int 3</CODE> for code that shouldn’t execute? appeared first on The Old New Thing.

"With the push to eliminate the twice yearly clock change, Permanent Daylight Savings Time has emerged as the favorite for most states and provinces," writes longtime Slashdot reader kbahey, sharing the findings from a recent analysis published in the Canadian Medical Association Journal. Sci.News reports: "Ending the clock change solves one problem, but it creates another decision: which time should we live on year-round?" said University of British Columbia's Professor Raymond Lam, lead author of the study. "The health evidence points to standard time, largely because morning light matters for our body clocks, sleep, and mood." Professor Lam and colleagues examined the health consequences of the two possible permanent systems rather than the broader question of whether seasonal clock changes should be abolished. They concluded that the accumulated evidence favors permanent standard time, which keeps the clock more closely aligned with human circadian biology. This distinction, according to the team, becomes particularly important during winter. Permanent daylight saving time would push sunrise an hour later. In cities such as Toronto, for example, the latest winter sunrise would occur at 8:51 a.m., compared with 7:51 a.m. under permanent standard time. In Calgary, the corresponding times would be 9:40 a.m. and 8:40 a.m. The extra hour of morning darkness could leave people traveling to work or school before sunrise, while shifting more daylight into the evening. The change could have consequences for sleep, mood, learning and productivity, particularly among people who already have difficulty sleeping or who must follow early schedules. The reason is rooted in the body's internal clock. "Our biological clocks need morning light to stay synchronized with the 24-hour day," said Simon Fraser University's Professor Ralph Mistlberger, co-author of the study. "Permanent daylight saving time moves that light an hour later just when winter mornings are already darkest." The analysis also highlights concerns about seasonal depression. [...] By delaying natural morning light, permanent daylight saving time would act in the opposite direction, potentially weakening an important circadian signal.

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As bipartisan backlash against Flock grows, some cities are asking anti-surveillance advocates and media outlets to pay eye-popping fees—including charging tens of thousands or even millions—to get information about how police departments are using and potentially abusing AI-enabled camera systems that track every vehicle that passes them.

On Monday, the Texas Tribune reported that city officials in a Fort Worth suburb, North Richland Hills, asked one group to pay $2.3 million before it would fulfill a public records request for Flock data. To reach that high fee, officials claimed that searching “about a terabyte worth of communications about errors, misuse, and effectiveness of the Flock system” would take approximately 14 years of labor at a rate of $15 per hour.

Phil Mynona, who filed the request using a pseudonym on behalf of his group, the Texas Privacy Coalition, told the Tribune that the fee seemed “ludicrous” and designed to stifle his public records searches.

Mynona has sought similar records from more than 200 law enforcement agencies across the US, and he said it was impossible to predict how cities assessed fees for Flock records. Some cities provided more than 400,000 pages of documents for free, while others charged $5,000. Other groups, including a Houston news station called KPRC, have seen officials quote up to $121,000 for Flock records, the Tribune reported.

The high price tags may be hiding data that anti-surveillance groups note have triggered audits, arrests, and changes in how law enforcement uses cameras, including decisions to get rid of cameras. Many cops have been found using the cameras to stalk strangers and people in their personal lives, and so far, Flock has yet to introduce meaningful reforms to confront its stalker cop problem.

Texas is a perfect example of how increasing transparency about police use of Flock cameras works to protect the public from invasive searches that serve no lawful purpose. Last week, an ex-Texas cop, Zachary Anthony Klein, reportedly pled guilty to 100 felony counts of misuse of official information, which he agreed to do in exchange for the state not pursuing charges related to stalking several people. Klein’s Flock abuse—along with another cop’s—was outed after USA Today submitted a public records request that sparked a probe, then his arrest. Disturbed by the case, Texas Governor Greg Abbott quickly halted Flock funding and stopped issuing permits, the Tribune noted.

Additionally concerning are officials who deny requests outright. Consider that the Tribune reported that the state Department of Public Safety has sought help from “the Attorney General’s Office to allow it to withhold the entirety” of Flock data that the Texas Tribune has requested. And that denial came after DPS had already responded to an identical request seeking data from prior weeks, the Tribune noted.

Flock misuse recently ruled unconstitutional

Flock maintains that its automated license plate readers (ALPR) are designed for public safety, while courts have largely agreed that cops can reasonably access Flock databases without infringing Fourth Amendment rights. But ongoingly, there are cases dominating the headlines that show a widening web of privacy risks, including not just illegal surveillance by police but also hackers or bad actors improperly accessing data that can be used to track people’s daily movements.

Courts may start to rethink their stance on Flock, with one federal judge in Oklahoma last week ruling that a cop conducted an unconstitutional search when searching a Flock database simply because a woman’s license plate was from California,” 404 Media reported.

That judge, Sara Hill, argued that Flock’s network “is a type of indiscriminate mass surveillance,” with its ALPR technology creating a “large-scale, dragnet-type surveillance system” that should require a warrant to search.

A Flock spokesperson told 404 Media that the company had nothing to do with the case but expects Hill’s ruling to be an outlier that will likely be appealed and overturned.

Importantly, Hill’s decision does not set any precedent, but it could be influential as one of the first to recognize that Flock searches can be unconstitutional. 404 Media said they reviewed audits showing “there are currently more than a hundred thousand warrantless searches of the Flock system every month.” Sometimes innocent people are arrested, including one man jailed for a month based on a Flock alert that he argued should have itself provided the evidence cops needed to see that he was innocent and five miles away from the crime scene.

For members of the public increasingly scrutinizing Flock cameras over unconstitutional searches and other privacy concerns, it’s hard to know basic things, like where the cameras are posted, who’s looking at the footage, how often the data is accessed, and how long the data is stored.

Public records requests can help answer these questions, and sometimes police choose to voluntarily share it, using optional “transparency portals” that Flock builds. Those portals log statistics like total number of cameras, vehicles scanned, or police searches in a given area.

Flock spokesperson Andrew Smith told the Texas Tribune that the portals “give agencies a public-facing way to publish information about their [ALPR] programs, including policies, usage, and access rules to help communities better understand how the technology is being used.”

However, very few agencies seem to be opting in to the sharing. In Texas, there are hundreds of agencies using Flock cameras, and only 59 agencies use transparency portals, the Tribune reported. Of those, just 16 share data with the public.

Without courts requiring warrants or state and local officials requiring more transparency, Flock cameras will continue tracking movements in ways that the public doesn’t fully understand, advocates warn. And new privacy risks may emerge as AI makes it easier to process data across the ever-broadening network.

Michael Soyfer is a lawyer at the Institute for Justice who “has studied Flock camera abuse and is litigating several cases on Fourth Amendment grounds,” 404 Media noted. He suggested that without more transparency on how police are using the cameras, Flock may end up building tools to support some of these police misuses the public dislikes, such as automating the type of alerts used when tracking vehicle movements that have raised false suspicions or caused wrongful arrests.

“We’re seeing that repeatedly with police flagging whatever they’ll call suspicious patterns of movement. Federal agents were using ALPRs to monitor cars making day trips across the border and back to manufacture a basis to stop them, interrogate the drivers, and search them,” Soyfer told 404 Media. “I think Flock is going to automate that, using AI where cops can set alerts for those kinds of travel patterns."

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Cable lobby groups notified the Federal Communications Commission that they will sue the agency to block its controversial repeal of the National Television Ownership Rule, which limits the number of broadcast TV stations a single company may own.

The cable groups said that larger broadcast TV station groups will have leverage to demand higher retransmission fees from TV providers, resulting in "higher monthly TV bills for consumers." They said the FCC repeal order "arbitrarily and capriciously ignores the harms that will surely follow from allowing broadcast station groups to exceed the National Cap."

The cable lobby groups represent top providers Comcast, Charter, and various other cable operators. Top cable companies have also expanded through mergers. Charter completed a purchase of Cox in August after the FCC rejected protests by advocacy groups that said the cable deal "would create unchecked gatekeeper power over Internet distribution" and make it easier for the biggest cable companies to raise prices.

The FCC voted to eliminate the TV ownership rule on August 6, and finally published the repeal order on its website on October 1 after an unusually long delay. The delay may be explained by the FCC shoring up its legal arguments in anticipation of lawsuits because the agency is claiming authority to repeal a limit set by Congress over 20 years ago.

FCC Chairman Brendan Carr has said that replacing a strict ownership limit with a “case-by-case review” of each proposed merger will let the agency approve deals that promote the public interest while rejecting deals that do not. Given Carr's history of threatening to revoke licenses from broadcasters disfavored by President Trump, case-by-case reviews would let Carr influence news coverage of the administration by allowing favored broadcast companies to expand.

Cable lobby petition

The TV ownership rule prohibits any single broadcast station owner from reaching more than 39 percent of all TV households in the US. Congress directed the FCC to set the cap at 39 percent in 2004. On Friday, cable lobby groups submitted a petition asking the FCC to keep the TV ownership cap in place until litigation over the FCC's authority to repeal the rule is over.

The cable groups' filing said the FCC repeal of the TV ownership cap violates the 2004 action by US lawmakers. The decision by Congress to set the cap at a precise numerical threshold was unambiguous, the filing said.

"Congress established the National Cap at 39 percent in the 2004 CAA [Consolidated Appropriations Act] in direct response to the FCC’s attempt to aggressively raise the Cap to 45 percent and made repeated references to the 39 percent Cap in the statute," the petition said.

The petition to the FCC is mainly a procedural step as the commission isn't likely to stay its own order. The cable groups said they intend to sue the commission in a US appeals court once the FCC order is published in the Federal Register. After the lawsuit is filed, they can ask the court to issue a preliminary injunction that would keep the TV ownership cap in place pending the outcome of litigation.

The filing was submitted by cable industry groups that represent providers in Colorado, Florida, Indiana, Michigan, Minnesota, Mississippi, Pennsylvania, Virginia, Washington, and the six New England states. The state and regional groups represent large and small cable companies, including the nation's biggest cable operators Comcast, Charter, and Cox.

FCC says it can change or eliminate rule

The FCC order published last week said that although Congress chose the 39 percent limit, the law set the limit by "directing the Commission to modify its rules rather than by enacting a fixed cap into law." The FCC argues it "has the authority and obligation to reexamine the national cap rule in response to changing circumstances and to modify or repeal it if it no longer serves the public interest."

While the 2004 law states the FCC cannot repeal or modify the cap during its quadrennial reviews of media rules, the FCC argues it can eliminate the cap if it does so outside the quadrennial review process. The law "simply separates the Commission’s decisions to review the national cap from the statutorily mandated review of other media ownership rules that are to occur every four years," the FCC said.

The cable groups' petition said the FCC can't change the cap because the 2004 law "references the 39 percent Cap as statutory, not regulatory." A provision requiring divestiture of stations "specified that someone exceeding 'the 39 percent national audience reach limitation in paragraph (1)(B)' of 'section 202(c)' of '[t]he Telecommunications Act of 1996' 'shall have not more than 2 years to divest,'" the petition said.

"Likewise, Congress singled out the Commission’s only mechanism for setting aside statutory requirements—the Commission’s forbearance authority under 47 U.S.C. § 160—and made clear that it 'shall not apply to any person or entity that exceeds the 39 percent national audience reach limitation,'" the cable lobby petition said. The FCC order argued that the agency's "ability to forbear from enforcement of its rules is distinct from its power to alter or eliminate those rules," and that the FCC forbearance authority doesn't apply to regulation of broadcasters.

FCC may face multiple lawsuits

Cable lobby groups aren't the only ones likely to sue the FCC. After the August FCC vote, media advocacy group Free Press said it plans to join with allies "to appeal this unlawful decision in court."

“Changing this limit requires congressional action, but Carr doesn’t care,” Free Press General Counsel Matt Wood said at the time. “He’ll do whatever it takes to clear the way for Trump-aligned billionaires to swallow up stations wherever and whenever they please. The result would be just one or two dominant broadcasters in every market, deep job cuts for journalists, and an influx of bargain-basement content disguised as local news.”

Even before repealing the TV ownership cap, the Carr FCC waived the rule when it approved the Nexstar Media Group purchase of Tegna. The Nexstar/Tegna combination would reach 80 percent of TV households in the US, or 54.5 percent when applying what’s known as the “UHF discount" in which only half of the households reached by a UHF station are counted toward the limit.

A federal judge ordered Nexstar and Tegna to stop integrating their assets and operations while an antitrust lawsuit filed by DirecTV proceeds. The petition from cable groups said the judge "found that the Nexstar/Tegna transaction would result in higher retransmission consent fees, causing harm to consumers, and issued a preliminary injunction that keeps the companies separate to this day." The groups said the harms from the Nexstar/Tegna deal are "merely a preview of the further massive broadcast industry consolidation and higher consumer prices that will follow if this Order [to repeal the national limit] is not stayed."

Disclosure: The Advance/Newhouse Partnership, which owns 14 percent of Charter, is part of Advance Publications, which owns Ars Technica parent Condé Nast.

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The Wikimedia Foundation says it found evidence that "rogue" OpenAI agents edited Wikimedia wikis without approval, unsuccessfully tried to exploit its Etherpad service, and generated millions of automated requests across Wikimedia projects. Here's a summary of what Wikimedia observed (via The Verge): Wiki editing: We've identified edits to Wikimedia wikis that we believe are from AI agents operated by OpenAI. These edits were not published to pages with visibility to general readers; almost all of them were testing edits in "sandbox" areas of the wiki. It also included a few edits to the configuration for a citation tool, which we believe were potentially malicious edits that were intended to misuse this tool as a proxy for fetching data from remote services. While Wikipedia policies allow bots to edit when they are disclosed and approved by the community, none of those approvals were sought in these incidents. Etherpad probing and use: Agents we believe to be operated by OpenAI made some unsuccessful attempts to compromise our public Etherpad, a note-taking tool we host as a community service. Agents unsuccessfully tried to use it to fetch data from other websites as a proxy. Other agents also likely operated by OpenAI took notes about their tasks, though this did not appear to turn into coordination. Excessive data downloading: Agents we believe to be operated by OpenAI made millions of automated requests to our public APIs to access the knowledge on Wikimedia projects, crawled millions of pages (mainly from our projects Wikidata and Wikimedia Commons), and made hundreds of thousands of data queries to the Wikidata Query Service (WQDS). This traffic may have contributed to a partial outage on WQDS in May.

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Wired reports that rural data center projects could become eligible for expanded federal Opportunity Zone tax benefits starting in 2027, with more than 100 planned or developing facilities potentially qualifying. "Right now, the only requirement to get the benefits is capital investment," says Emily Kraschel, a tax policy analyst at the Searchlight Institute, a public policy think tank. "However, that doesn't guarantee that that money is necessarily creating jobs or creating a local economic boost. You'd be more sure of that with a more traditional factory that requires lots of workers. But with a data center, that assumption goes a little wonky." From the report: During the first Trump administration, a bipartisan group of lawmakers proposed the creation of the opportunity zone program, which offers tax benefits for companies that choose to build projects in certain low-income census tracts. Last year, the One Big Beautiful Bill Act made a number of changes to open up the program in order to attract more investment to rural areas. Kraschel and her colleagues from Searchlight have been researching data center projects that might qualify for these tax benefits, comparing the locations of data center projects in development with rural census tracts eligible for the new program. Wired exclusively reviewed the research compiled by Searchlight and found more than 100 data centers under various stages of development in rural areas that could be eligible. Searchlight used a very conservative database of under 700 data center projects that are planned or under construction to compile its research; other datasets put the number of data centers in development in the US at closer to 1,500. It's very likely that the number of newly eligible projects is bigger, especially since more data centers are decamping from urban areas. Separate research from Pew found that while just 13 percent of operating data centers are located in rural areas, a majority of planned facilities -- around 67 percent -- are going rural. [...] A project simply existing in a rural opportunity zone doesn't mean the company automatically will get the tax benefits; the company has to create a specialized investment vehicle to kickstart the process. Because the tax break can be considered confidential IRS data, it's next to impossible to know which companies are pursuing the benefits unless they voluntarily disclose. [...] Nathan Jensen, a government professor at the University of Texas-Austin, says that he would be "very surprised" if some companies were not considering siting in rural opportunity zones as part of their decisionmaking process. "It's essentially free money," he says. There is no requirement for projects getting opportunity zone benefits to create jobs; the assumption is that they will do so, simply by siting in the community itself. This isn't always the case for projects like storage facilities and warehouses, which, Jensen says, have been popular choices for developers working in opportunity zones. Data centers may create a number of jobs in the short term for their construction, but there's an ongoing debate about whether or not they create a lasting new workforce over the longer term.

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