Rename CONFIG_DEBUG_LIST better and default=y

[kees]

CONFIG_DEBUG_LIST has been enabled in distros for a long time. It should be switched to default=y and likely named something better, like CONFIG_HARDENED_LIST.

[kees]

Evidence that this has real-world defensive impact:
https://bugs.chromium.org/p/project-zero/issues/detail?id=1942

[willdeacon]

I've started looking at this, so feel free to assign this to me if you like.

[willdeacon]

RFC: https://lore.kernel.org/lkml/20200324153643.15527-1-will@kernel.org/T/#t

Will definitely need more work, but it's a start. I haven't done the default=y because I've added a bunch of extra checks and we'd probably need performance data to justify enabling them by default.

[kees]

What's the status of this series? It looks like it was pretty close to landing from the RFC.

[willdeacon]

I got stuck because some of the code is shared between the synchronized and RCU/lockless paths:

https://lore.kernel.org/r/20200424173932.GK21141@willie-the-truck

But I agree that I should try to dust this back off and see if I can figure it out again.

[kees]

Ping -- what's left for this series to land?

[kees]

Who would be best to help solve the RCU/lockless paths?

[melver]

I found CONFIG_DEBUG_LIST to have measurable performance impact in some cases. FTR, attempts to optimize it: https://lkml.kernel.org/r/20230808102049.465864-1-elver@google.com

[kees]

CONFIG_LIST_HARDENED has been landed in commit aebc7b0.