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

[Peter Zijlstra]

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.