Date: Thu, 07 Aug 2014 19:07:15 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 192487] New: cpucontrol uses unsafe procedure to detect current microcode version Message-ID: <bug-192487-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=192487 Bug ID: 192487 Summary: cpucontrol uses unsafe procedure to detect current microcode version Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: Needs Triage Severity: Affects Many People Priority: --- Component: bin Assignee: freebsd-bugs@FreeBSD.org Reporter: hmh+freebsd@hmh.eng.br The Intel SDM, vol 3A, section 9.11.7.1, defines a procedure that should be followed to ensure a valid response from the System Processor when it is queried about the running microcode revision. The userspace cpucontrol utility fails to follow this procedure. cpucontrol fails to pre-init MSR 0x8B (MSR_BIOS_SIGN) with zero and issue a cpuid(1), before it can get valid data from that same MSR. Please refer to example 9-9 in the Intel SDM vol 3A page 9-36. I have no idea how important this procedure is on current Intel processors, but the impact of getting garbage from MSR_BIOS_SIGN includes either incorrectly downgrading, or incorrectly refusing to upgrade microcode. The bug is in file: usr.sbin/cpucontrol/intel.c -- You are receiving this mail because: You are the assignee for the bug.
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