Intel has admitted that PCs and servers are experiencing unexpected reboots after applying a patch designed to address the Spectre and Meltdown processor flaws. Spectre and Meltdown are design flaws in modern CPUs that could allow hackers to bypass system protections on a wide range of devices, allowing attackers to read sensitive information, such as passwords, from memory. Intel began making software and firmware updates available to mitigate attacks exploiting these flaws last week, pushing them out via system manufacturers. However, yesterday the chip maker admitted these updates were causing certain computers to unexpectedly reboot. The random reboots appear to be affecting both PCs and servers that use Intel Broadwell and Haswell processors. "We are working quickly with these customers to understand, diagnose and address this reboot issue. If this requires a revised firmware update from Intel, we will distribute that update through the normal channels," wrote Navin Shenoy, executive vice president and general manager of the Data Center Group at Intel. Despite the issues, Shenoy says that computer users and admins should "continue to apply updates recommended by their system and operating system providers". While tech firms have been preparing updates to mitigate the Spectre and Meltdown flaws for months, details of the vulnerabilities leaked out early. In the rush to issue patches there have been other instances of Spectre and Meltdown updates causing problems of their own. Microsoft recently said that Windows PCs won't receive any further security updates until third-party AV software is verified as compatible with Windows patches for Spectre and Meltdown. And chipmaker AMD has been working with Microsoft to resolve problems after the patches caused PCs running on some older AMD Opteron, Athlon and AMD Turion X2 Ultra processors to refuse to boot. AMD said yesterday the issue should be resolved shortly. AMD also announced that, starting this week, it will address the branch target injection exploit for Spectre by making microcode updates available for its Ryzen and Epyc processors. Updates for older processors will follow in the "coming weeks", with all updates being made available via OS vendors and system manufacturers. The Meltdown flaw doesn't affect AMD processors. As well as triggering undesirable behaviour the Spectre patches are degrading machine performance, particularly for older processors. Microsoft said earlier this week that people running computers on 2015-era Intel Haswell or earlier processors would see the biggest performance slowdown, particularly if they weren't using Windows 10. Those running Windows 10 systems on newer CPUs would see minimal impact, it said. Microsoft cautioned the performance of Windows Server systems could suffer a more significant impact, "especially in any IO-intensive application". Intel has also published data, gathered both from users and its own synthetic benchmarks, which identified a real-world performance hit of between about six and eight percent across all systems. Like Microsoft, it found that computers running on 8th-generation processors suffered a smaller impact than those running 7th- or 6th-generation CPUs. Apple claims that performance of Macs, iPhones and iPads is largely unaffected by the patches, stating "our testing with public benchmarks has shown that the changes in the December 2017 updates resulted in no measurable reduction in the performance of macOS and iOS as measured by the GeekBench 4 benchmark, or in common Web browsing benchmarks". Major cloud providers, AWS, Google and Microsoft say that, for the majority of workloads, customers should not notice a difference in performance following the updates. However, there have been reports from some customers of a drop off. AWS customer Epic Games attributed a more than 20 percent spike in CPU load on a cloud server hosting games of Fortnite to the impact of the Spectre and Meltdown patches. Also see
Intel told some customers to hold off on installing its updates. Earlier this week, Intel said it would have Meltdown and Spectre fixes available by the end of the month for all recently made chips. But as the Wall Street Journal reports, some of the patches the company has released have caused some problems of their own. Some firmware updates are apparently causing computers to reboot. The Wall Street Journal got its hands on a document Intel was sharing with some of its customers (see note below), in which it advised them to "delay additional deployments of these microcode updates." Stephen Smith, Intel's data-center group general manager, told the publication that the bugs didn't have anything to do with security and that the document was being shared with computer makers and large cloud providers. Since the Wall Street Journal published its report, Intel has released a blog post explaining the systems affected by the reboots are running Broadwell and Haswell CPUs. "We are working quickly with these customers to understand, diagnose and address this reboot issue," it said. Microsoft also halted some of its updates earlier this week after some AMD computer users reported that they couldn't boot their computers after installing its patch. And Intel reported that most people would experience a small amount of slowdown -- less than 10 percent -- on their personal computers after installing its fix. One of Intel's partners told the Wall Street Journal that only telling some of its customers about the issue was a bad move on the part of Intel, saying the public has "been given the microcode update but has not been given the important technical information that Intel recommends that you don't use this." But security researcher Paul Kocher, who discovered some of the issues with Intel's chips, said this sort of thing is to be expected. " It doesn't surprise me a lot that there would be some hiccups." Update: While the Wall Street Journal reported that only some of Intel's customers were receiving notice that they may want to hold off on installing its updates, Intel tells us that all of its customers were notified. The notice "was sent to all customers through the standard patch notification process," a spokesperson told us.