On Mon, 19 Aug 2024 at 12:23, Barry Song [off-list ref] wrote:

That could be an exploit taking advantage of those improper callers,

So?

FIX THE BUGGY CODE.

Don't make insane and incorrect changes to the MM code and spread
Fear, Uncertainty and Doubt.

thus it wouldn’t necessarily result in an immediate oops in callers but
result in an exploit

No. Any bug can be an exploit. Don't try to make this something
special by calling it an exploit.

NULL pointer dereferences are some of the *least* worrisome bugs,
because we don't allow people to mmap the NULL area anyway.

So just stop spreading FUD. We don't improve the kernel by making
excuses for bugs, we improve it by fixing things.

And any caller that asks for NOFAIL with bad parameters is buggy. The
MM code should NOT try to fix it up, and dammit, BUG_ON() is not
acceptable as a debugging help. Never was, never will be.

Worry-warts already do "reboot-on-warn".

            Linus