Messages in this thread | | | Subject | Re: [syzbot] KASAN: stack-out-of-bounds Read in profile_pc | From | Andi Kleen <> | Date | Wed, 2 Jun 2021 16:35:11 -0700 |
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> profile_pc() assumes the return address is either directly at regs->sp, > or one word adjacent to it due to saved flags, both of which are just > completely wrong. This code has probably never worked with ORC, and > nobody noticed apparently.
I presume it used to work because the lock functions were really simple, but that's not true anymore.
> > We could just use ORC to unwind to the next frame. Though, isn't > /proc/profile redundant, compared to all the more sophisticated options > nowadays? Is there still a distinct use case for it or can we just > remove it?
It's still needed for some special cases. For example there is no other viable way to profile early boot without a VM
I would just drop the hack to unwind, at least for the early boot profile use case locking profiling is usually not needed.
-Andi
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