Messages in this thread | | | Date | Thu, 3 Jun 2021 08:29:58 -0500 | From | Josh Poimboeuf <> | Subject | Re: [syzbot] KASAN: stack-out-of-bounds Read in profile_pc |
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On Wed, Jun 02, 2021 at 04:35:11PM -0700, Andi Kleen wrote: > > > 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.
Yeah, I figured as much.
> > 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.
Ok, I'll just get rid of the hack then.
-- Josh
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