lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 16 May 2019 16:55:33 +0100
From:   Ben Hutchings <>
CC:, Denis Kirjanov <>,
        "Josh Poimboeuf" <>,
        "Konrad Rzeszutek Wilk" <>,
        "Thomas Gleixner" <>,
        "Tyler Hicks" <>
Subject: [PATCH 3.16 78/86] x86/speculation/mds: Print SMT vulnerable on
 MSBDS with mitigations off

3.16.68-rc1 review patch.  If anyone has any objections, please let me know.


From: Konrad Rzeszutek Wilk <>

commit e2c3c94788b08891dcf3dbe608f9880523ecd71b upstream.

This code is only for CPUs which are affected by MSBDS, but are *not*
affected by the other two MDS issues.

For such CPUs, enabling the mds_idle_clear mitigation is enough to
mitigate SMT.

However if user boots with 'mds=off' and still has SMT enabled, we should
not report that SMT is mitigated:

$cat /sys//devices/system/cpu/vulnerabilities/mds
Vulnerable; SMT mitigated

But rather:
Vulnerable; SMT vulnerable

Signed-off-by: Konrad Rzeszutek Wilk <>
Signed-off-by: Thomas Gleixner <>
Reviewed-by: Tyler Hicks <>
Reviewed-by: Josh Poimboeuf <>
Signed-off-by: Ben Hutchings <>
 arch/x86/kernel/cpu/bugs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1156,7 +1156,8 @@ static ssize_t mds_show_state(char *buf)
 	if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
 		return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
-			       sched_smt_active() ? "mitigated" : "disabled");
+			       (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" :
+			        sched_smt_active() ? "mitigated" : "disabled"));
 	return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],

Powered by blists - more mailing lists