Re: BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530

[Arnaldo Carvalho de Melo]

Em Thu, Nov 30, 2017 at 09:20:26AM +0100, Peter Zijlstra escreveu:
> On Thu, Nov 30, 2017 at 10:32:19AM +0800, Fengguang Wu wrote:
> > Hello,
> > 
> > FYI this happens in mainline kernel 4.15.0-rc1.
> > It looks like a new regression and hard to bisect.
> > 
> > It occurs in 1 out of 57 boots.
> > 
> > [   10.009610] chown (367) used greatest stack depth: 26944 bytes left
> > Kernel tests: Boot OK!
> > [   30.357729] trinity-main uses obsolete (PF_INET,SOCK_PACKET)
> > [   31.301433] sock: process `trinity-main' is using obsolete setsockopt SO_BSDCOMPAT
> > [   31.310289] ==================================================================
> > [   31.311490] BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530:
> > 						perf_callchain_store at include/linux/perf_event.h:1128
> > 						 (inlined by) perf_callchain_user at arch/x86/events/core.c:2485
> 
> I don't think we recently changed anything here...
> 
> But I do have vague memories of something being off here; I never quite
> could penetrate the max_stack / contexts_maxed stuff, and istr acme was
> going to have a peek.
 
Sure, but I saw some backward ring buffer stuff in there as well, no?
IIRC that came after the max-stack code, Adding Wang to the CC list.

- Arnaldo