4.4-stable review patch. If anyone has any objections, please let me know.
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From: Tony Luck tony.luck@intel.com
commit d28af26faa0b1daf3c692603d46bc4687c16f19e upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/cpu/mcheck/mce.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -670,6 +670,7 @@ static int mce_no_way_out(struct mce *m, }
if (mce_severity(m, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) { + m->bank = i; *msg = tmp; ret = 1; }