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Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

bugzilla.mozilla.org

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Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#72

Post by TecoAndJix »

_8j50 wrote: post #44
whalesalad wrote: post #39

My only interaction with Windows Defender is the (undefeatable) nag popup every boot that warns me it is disabled.

Haha, you should enable it with exclusions. It's the best AV out there that isn't an EDR. I disable it in labs but I can't imagine running windows in prod with defender enabled. Don't use windows like it's Linux.

Defender, under certain licenses, is an EDR - https://learn.microsoft.com/en-us/microsoft-365/security/def...

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#73

Post by jupp0r »

BuckRogers wrote: post #65
jupp0r wrote: post #26

Earlier quoted context omitted.

Did you read the bug report? This is literally about writing to files in a temp folder. Surely you can optimize that but you should also be able to assume that this does not use excessive amounts of CPU on a modern operating system.

You really shouldn’t assume anything in software or any complex system. I know this wouldn’t fly at my job, and I don’t work at Mozilla. This is basic testing. Normally this is the mark of a bad software engineer, but attempting to blame the platform you’re on for your lack of testing takes it a to a new low. Mistakes happen, admitting full incompetence that basic testing isn’t done is damning. This is not a good def…

Not sure what your job is, but in my job:

- we implement a feature, test it thoroughly for functional and non-functional requirements

- when we are happy, we release it

I don't see myself being responsible for a third party software company coming along years later and introducing a bug in code that injects itself between my software and the operating system that users of the software I wrote happens to install at some point.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#74

Post by [deleted] »

TecoAndJix wrote: post #72
_8j50 wrote: post #44

Earlier quoted context omitted.

Haha, you should enable it with exclusions. It's the best AV out there that isn't an EDR. I disable it in labs but I can't imagine running windows in prod with defender enabled. Don't use windows like it's Linux.

Defender, under certain licenses, is an EDR - https://learn.microsoft.com/en-us/microsoft-365/security/def...

[deleted]

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#76

Post by dylan604 »

pjmlp wrote: post #50
arnaudsm wrote: post #40

Quick napkin math of the wasted power : Firefox has ~300e6 users, let's assume the bug wasted 5 extra watts 4 hours a day. That's 250 megawatts saved, the equivalent of an average coal power plant. Because some Microsoft engineer missed a bug.

If it isn't on the Sprint board it doesn't exist.

You also have to assume that at least one Microsoft employee has Firefox installed. There's no bug if there's no users

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#77

Post by pavon »

jupp0r wrote: post #22
jeffbee wrote: post #9

That's one way to look at it, but a very biased take. An equally valid take is that Firefox was calling an expensive platform feature too often, and even though it has been killing performance for years (possibly, for the entire history of the project) nobody noticed or bothered to fix it on the application side.

Also worth noting that the "expensive platform feature" you refer to in this specific case means "writing to a file". Something as basic as this should be assumed to be fast on modern operating systems.

No it had nothing to do with Firefox writing files. Firefox was making a bunch of calls to VirtualProtect. Windows Defender (MsMpEng.exe) was then writing to file (an sqlite database) every time one of these calls was made, which was slowing down the system.

This comment is a good summary of what the issue was once they understood the problem: https://bugzilla.mozilla.org/show_bug.cgi?id=1441918#c82

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#78

Post by akira2501 »

ChuckNorris89 wrote: post #58
whalesalad wrote: post #39

My only interaction with Windows Defender is the (undefeatable) nag popup every boot that warns me it is disabled.

My car also nags me every time I unbuckle my seatbelt to park yet that doesn't mean everyone should have it unbuckled all the time. There's a reason it's designed to be naggy. Having everyone easily disable Windows Defender will not lead to a great outcome. There's a reason malware on Windows has been on a steep decline from the Windows XP days and I'd prefer it to keep it that way.

Not all uses cases for a car are the same. Some are held entirely on private property and are used as work vehicles where the seat belt chime would be unnecessary and distracting. Which is why most manufacturers provide a sneaky mechanism to disable it. I own the vehicle, why wouldn't they let me disable the nag?

Their solution? Make it intentionally complicated, but still possible:

Step 1: Turn your headlight switch off

Step 2: Unbuckle your seatbelt and turn the key to the off position

Step 3: Turn your key to the on position till the seatbelt warning light turns off

Step 4: Buckle and unbuckle the seatbelt three times and end on the unbuckled position

Step 5: Turn your headlight switch on for three seconds and then turn it off

Step 6: Repeat step number 3

Step 7: Wait for the seat belt warning light to turn on and off again then buckle and buckle the seat belt

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