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Car radios crashed by station broadcasting images with no file extension

Video killed the radio star, pictures came and broke your car

In January, drivers of older model Mazdas in the area around Seattle, Washington, started seeing their HD Radio receivers crash upon tuning to the local public radio station.

The issue, according to the Seattle Times, has affected 2014-2017 model year Mazdas with infotainment systems that support HD Radio. Tuning to KUOW, which resides at 94.9 on the FM dial, caused some Mazda in-vehicle infotainment systems to fail.

In threads on Reddit, people report that the issue manifests in various ways: some describe a frozen radio display screen, others tell of endless reboot loops. The problem has also resulted in radios being stuck on KUOW, which the public radio station says it's trying to help resolve.

"KUOW is aware of an apparent issue between our signal and some Mazda infotainment systems, causing radios to reboot when they connect to KUOW’s 94.9 FM signal," the radio broadcaster said in a statement. "We have been in contact with Xperi, the company who owns the technology behind HD Radio, and have given them complete access to our transmitters to investigate what is causing this issue."

KUOW said its operations team is trying to get the issue resolved.

And to hear Xperi and Madza tell it, the broadcaster is to blame for transmitting images – which show up on HD Radio display screens – without the required file extension in the file name.

Xperi attributed the problem to the way KUOW sent its data.

"Our current assessment is that there was a formatting issue with the transmitted data," a company spokesperson told The Register in an email. "We have worked with the station to address it, and we do not believe there are any ongoing issues with car radios in the market."

Mazda too indicated that the transmission killed the radios in its cars.

"Between 1/24-1/31, a radio station in the Seattle area sent image files with no extension (e.g., missing .jpeg or .gif), which caused an issue on some 2014-2017 Mazda vehicles with older software," the company said. "Mazda North American Operations (MNAO) has distributed service alerts advising dealers of the issue."

"While dealers are currently experiencing parts delays due to shipping constraints, MNAO will support impacted customers with replacement parts. These customers should contact their local Mazda dealer who can submit a goodwill request to the Mazda Warranty department on their behalf, order the parts, and schedule a free repair when the parts arrive."

According to the Seattle Times, Lorenzo Pieruccioni, service manager at Mazda of Olympia, Washington, said he'd seen several customers come in with radio problems, which he attributed to a corrupt Connectivity Master Unit (CMU).

The CMU moderates the flow of video and audio signals to the infotainment system. It costs $1,500 normally, but it remains scarce due to supply chain issues.

Implicit in Mazda's statement is the admission that older versions of the software in its infotainment system fail to sufficiently validate inputs, thereby allowing malformed data to crash the device.

Mazda and Xperi didn't immediately respond to a request to clarify which software version fixed this issue for more recent vehicles. But if Mazda's answer is a hardware replacement, it would appear that a software update isn't an option.

The 99% Invisible podcast in 2019 explored a separate bug related to printf format string handling that affected the infotainment system in a 2016 Mazda sedan. ®

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