Option to clear allocated kernel memory before freeing it?

[Michael Opdenacker <michael-lists@free-electrons.com>]

Hello,

Would it make sense to implement a kernel option that would clear kernel 
memory before freeing it (by kfree or free_page(s))?

Unless I'm missing something, uncleared memory previously used for 
kernel allocations could later be recycled for user allocations, making 
it possible for a user program to access sensitive driver data if it's 
lucky.

Tough clearing memory should be efficient (thanks to the use of 
memset(), optimized for each platform), there would of course be a 
significant performance hit. However, this could be acceptable for 
systems with strong security requirements...

What do you think? If this idea makes sense, I'll be glad to help in 
implementing it.

    Thanks in advance,

    Cheers,

    Michael.

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