Re: PROBLEM: syzkaller found / reduced C repro for non-fatal unchecked MSR access error

[Peter Zijlstra]

On Thu, Jan 10, 2019 at 11:21:16PM +0000, Esme wrote:
> Attached is a fairly small C repro I did not see any references to
> this possible flaw (unchecked MSR access) in relation to
> __NR_perf_event_open
> 
> Attached is the config directly extracted from proc.  This is the call
> stack in relation to the MSR access error (5.0.0-rc1+), I get a very
> similar stack running this test case on a stock Ubuntu
> "4.18.0-11-generic" (pasted after this one).

> -- Esme
> 
> [   70.228744] unchecked MSR access error: WRMSR to 0xc0010000 (tried to write 0x0000020000130076) at rIP: 0xffffffff812dde28 (native_write_msr+0x8/0x30)

That's K7_EVNTSEL0. What kind of hardware are you running this on?