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enh: MDS FreeBSD: detect software mitigation as OK unless --paranoid (#503)

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Stéphane Lesimple
2026-04-06 00:17:32 +02:00
parent bbdf54cf7f
commit f5c42098c3
1 changed files with 28 additions and 2 deletions
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30
src/vulns-helpers/check_mds.sh
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@@ -53,7 +53,17 @@ check_mds_bsd() {
else
kernel_mds_state=inactive
fi
# https://github.com/freebsd/freebsd/blob/master/sys/x86/x86/cpu_machdep.c#L953
# possible values for hw.mds_disable_state (FreeBSD cpu_machdep.c):
# - inactive: no mitigation (non-Intel, disabled, or not needed)
# - VERW: microcode-based VERW instruction
# - software IvyBridge: SW sequence for Ivy Bridge
# - software Broadwell: SW sequence for Broadwell
# - software Skylake SSE: SW sequence for Skylake (SSE)
# - software Skylake AVX: SW sequence for Skylake (AVX)
# - software Skylake AVX512: SW sequence for Skylake (AVX-512)
# - software Silvermont: SW sequence for Silvermont
# - unknown: fallback if handler doesn't match any known
# ref: https://github.com/freebsd/freebsd-src/blob/main/sys/x86/x86/cpu_machdep.c
case "$kernel_mds_state" in
inactive) pstatus yellow NO ;;
VERW) pstatus green YES "with microcode support" ;;
@@ -85,7 +95,23 @@ check_mds_bsd() {
pvulnstatus "$cve" VULN "Your microcode supports mitigation, but your kernel doesn't, upgrade it to mitigate the vulnerability"
fi
else
if [ "$kernel_md_clear" = 1 ]; then
if [ "$kernel_md_clear" = 1 ] && [ "$opt_live" = 1 ]; then
# no MD_CLEAR in microcode, but FreeBSD may still have software-only mitigation active
case "$kernel_mds_state" in
software*)
if [ "$opt_paranoid" = 1 ]; then
pvulnstatus "$cve" VULN "Software-only mitigation is active, but in paranoid mode a microcode-based mitigation is required"
elif [ "$kernel_smt_allowed" = 1 ]; then
pvulnstatus "$cve" OK "Software-only mitigation is active, but SMT is enabled so cross-thread attacks are still possible"
else
pvulnstatus "$cve" OK "Software-only mitigation is active (no microcode update required for this CPU)"
fi
;;
*)
pvulnstatus "$cve" VULN "Your kernel supports mitigation, but your CPU microcode also needs to be updated to mitigate the vulnerability"
;;
esac
elif [ "$kernel_md_clear" = 1 ]; then
pvulnstatus "$cve" VULN "Your kernel supports mitigation, but your CPU microcode also needs to be updated to mitigate the vulnerability"
else
pvulnstatus "$cve" VULN "Neither your kernel or your microcode support mitigation, upgrade both to mitigate the vulnerability"