x86/MCE: Initialize mce.bank in the case of a fatal error in mce_no_way_out()
authorTony Luck <tony.luck@intel.com>
Fri, 1 Feb 2019 00:33:41 +0000 (16:33 -0800)
committerBorislav Petkov <bp@suse.de>
Sun, 3 Feb 2019 12:24:24 +0000 (13:24 +0100)
commitd28af26faa0b1daf3c692603d46bc4687c16f19e
treed8c7ac4f2ea27f837334368193fdf1711c4a1f7d
parente6d429313ea5c776d2e76b4494df69102e6b7115
x86/MCE: Initialize mce.bank in the case of a fatal error in mce_no_way_out()

Internal injection testing crashed with a console log that said:

  mce: [Hardware Error]: CPU 7: Machine Check Exception: f Bank 0: bd80000000100134

This caused a lot of head scratching because the MCACOD (bits 15:0) of
that status is a signature from an L1 data cache error. But Linux says
that it found it in "Bank 0", which on this model CPU only reports L1
instruction cache errors.

The answer was that Linux doesn't initialize "m->bank" in the case that
it finds a fatal error in the mce_no_way_out() pre-scan of banks. If
this was a local machine check, then this partially initialized struct
mce is being passed to mce_panic().

Fix is simple: just initialize m->bank in the case of a fatal error.

Fixes: 40c36e2741d7 ("x86/mce: Fix incorrect "Machine check from unknown source" message")
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: x86-ml <x86@kernel.org>
Cc: stable@vger.kernel.org # v4.18 Note pre-v5.0 arch/x86/kernel/cpu/mce/core.c was called arch/x86/kernel/cpu/mcheck/mce.c
Link: https://lkml.kernel.org/r/20190201003341.10638-1-tony.luck@intel.com
arch/x86/kernel/cpu/mce/core.c