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https://github.com/speed47/spectre-meltdown-checker
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feat(inception): kernel checks + sbpb support detection
This commit is contained in:
Sébastien Mériot
Stéphane Lesimple
parent
fb6933dc64
commit
ecee75716e
@ -2704,7 +2704,8 @@ sys_interface_check()
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# write_msr
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# param1 (mandatory): MSR, can be in hex or decimal.
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# param2 (optional): CPU index, starting from 0. Default 0.
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# param2 (optional): value to write, can be in hex or decimal.
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# param3 (optional): CPU index, starting from 0. Default 0.
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WRITE_MSR_RET_OK=0
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WRITE_MSR_RET_KO=1
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WRITE_MSR_RET_ERR=2
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@ -2740,6 +2741,8 @@ write_msr_one_core()
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_core="$1"
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_msr_dec=$(( $2 ))
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_msr=$(printf "0x%x" "$_msr_dec")
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_value_dec=$(( $3 ))
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_value=$(printf "0x%x" "$_value_dec")
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write_msr_msg='unknown error'
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: "${msr_locked_down:=0}"
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@ -2764,7 +2767,7 @@ write_msr_one_core()
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_write_denied=0
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if [ "$os" != Linux ]; then
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cpucontrol -m "$_msr=0" "/dev/cpuctl$_core" >/dev/null 2>&1; ret=$?
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cpucontrol -m "$_msr=$_value" "/dev/cpuctl$_core" >/dev/null 2>&1; ret=$?
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else
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# for Linux
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# convert to decimal
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@ -2774,16 +2777,16 @@ write_msr_one_core()
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# if wrmsr is available, use it
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elif command -v wrmsr >/dev/null 2>&1 && [ "${SMC_NO_WRMSR:-}" != 1 ]; then
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_debug "write_msr: using wrmsr"
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wrmsr $_msr_dec 0 2>/dev/null; ret=$?
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wrmsr $_msr_dec $_value_dec 2>/dev/null; ret=$?
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# ret=4: msr doesn't exist, ret=127: msr.allow_writes=off
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[ "$ret" = 127 ] && _write_denied=1
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# or fallback to dd if it supports seek_bytes, we prefer it over perl because we can tell the difference between EPERM and EIO
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elif dd if=/dev/null of=/dev/null bs=8 count=1 seek="$_msr_dec" oflag=seek_bytes 2>/dev/null && [ "${SMC_NO_DD:-}" != 1 ]; then
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_debug "write_msr: using dd"
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dd if=/dev/zero of=/dev/cpu/"$_core"/msr bs=8 count=1 seek="$_msr_dec" oflag=seek_bytes 2>/dev/null; ret=$?
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awk "BEGIN{printf \"\%c\", $_value_dec}" | dd of=/dev/cpu/"$_core"/msr bs=8 count=1 seek="$_msr_dec" oflag=seek_bytes 2>/dev/null; ret=$?
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# if it failed, inspect stderrto look for EPERM
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if [ "$ret" != 0 ]; then
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if dd if=/dev/zero of=/dev/cpu/"$_core"/msr bs=8 count=1 seek="$_msr_dec" oflag=seek_bytes 2>&1 | grep -qF 'Operation not permitted'; then
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if aws "BEGIN{printf \"%c\", $_value_dec}" | dd of=/dev/cpu/"$_core"/msr bs=8 count=1 seek="$_msr_dec" oflag=seek_bytes 2>&1 | grep -qF 'Operation not permitted'; then
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_write_denied=1
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fi
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fi
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@ -2791,7 +2794,7 @@ write_msr_one_core()
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elif command -v perl >/dev/null 2>&1 && [ "${SMC_NO_PERL:-}" != 1 ]; then
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_debug "write_msr: using perl"
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ret=1
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perl -e "open(M,'>','/dev/cpu/$_core/msr') and seek(M,$_msr_dec,0) and exit(syswrite(M,pack('H16',0)))"; [ $? -eq 8 ] && ret=0
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perl -e "open(M,'>','/dev/cpu/$_core/msr') and seek(M,$_msr_dec,0) and exit(syswrite(M,pack(v4,$_value_dec)))"; [ $? -eq 8 ] && ret=0
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else
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_debug "write_msr: got no wrmsr, perl or recent enough dd!"
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mockme=$(printf "%b\n%b" "$mockme" "SMC_MOCK_WRMSR_${_msr}_RET=$WRITE_MSR_RET_ERR")
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@ -2836,7 +2839,7 @@ write_msr_one_core()
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else
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ret=$WRITE_MSR_RET_KO
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fi
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_debug "write_msr: for cpu $_core on msr $_msr, ret=$ret"
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_debug "write_msr: for cpu $_core on msr $_msr, value=$_value, ret=$ret"
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mockme=$(printf "%b\n%b" "$mockme" "SMC_MOCK_WRMSR_${_msr}_RET=$ret")
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return $ret
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}
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@ -3530,6 +3533,28 @@ check_cpu()
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fi
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if is_amd || is_hygon; then
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_info " * Selective Branch Predictor Barrier (SBPB)"
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_info_nol " * PRED_CMD MSR is available: "
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if [ "$opt_allow_msr_write" = 1 ]; then
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# the MSR PRED_SBPB is at offset 0x49, BIT(7), write-only
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write_msr 0x49 128; ret=$?
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if [ $ret = $WRITE_MSR_RET_OK ]; then
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pstatus green YES
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cpuid_sbpb=1
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elif [ $ret = $WRITE_MSR_RET_KO ]; then
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pstatus yellow NO
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else
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pstatus yellow UNKNOWN "$write_msr_msg"
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cpuid_sbpb=3
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fi
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else
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pstatus yellow UNKNOWN "not allowed to write msr"
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cpuid_sbpb=3
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fi
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fi
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_info_nol " * CPU supports Transactional Synchronization Extensions (TSX): "
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ret=$READ_CPUID_RET_KO
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cpuid_rtm=0
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@ -6334,6 +6359,28 @@ check_CVE_2023_20569_linux() {
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pstatus yellow NO
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fi
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_info_nol "* Kernel compiled with SRSO support "
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if [ -r "$opt_config" ]; then
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if grep -q '^CONFIG_CPU_SRSO=y' "$opt_config"; then
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pstatus green YES
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else
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pstatus yellow NO "required for safe RET and ibpb_on_vmexit mitigations"
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fi
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else
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pstatus yellow UNKNOWN "couldn't read your kernel configuration"
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fi
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_info_nol "* Kernel compiled with IBPB support "
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if [ -r "$opt_config" ]; then
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if grep -q '^CONFIG_CPU_IBPB_ENTRY=y' "$opt_config"; then
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pstatus green YES
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else
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pstatus yellow NO "required for ibpb mitigation"
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fi
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else
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pstatus yellow UNKNOWN "couldn't read your kernel configuration"
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fi
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if [ -n "$kernel_sro" ]; then
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# TODO check mitigation
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@ -6342,20 +6389,30 @@ check_CVE_2023_20569_linux() {
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# Zen & Zen2 : if the right IBPB microcode applied + SMT off --> not vuln
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if [ "$cpu_family" = $(( 0x17 )) ]; then
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_info_nol "* IBPB support: "
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_info_nol " * IBPB support: "
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if [ -n "$cpuid_ibpb" ]; then
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pstatus green YES "$cpuid_ibpb"
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else
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pstatus red NO
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fi
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_info_nol "* SMT is enabled: "
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_info_nol " * SMT is enabled: "
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is_cpu_smt_enabled; smt_enabled=$?
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if [ "$smt_enabled" = 0 ]; then
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pstatus red YES
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else
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pstatus green NO
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fi
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# Zen 3/4 microcode brings SBPB mitigation
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elif [ "$cpu_family" = $(( 0x19 )) ]; then
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_info_nol "* CPU supports SBPB: "
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if [ "$cpuid_sbpb" = 1 ]; then
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pstatus green YES
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elif [ "$cpuid_sbpb" = 3 ]; then
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pstatus yellow UNKNOWN "cannot write MSR"
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else
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pstatus yellow NO
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fi
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fi
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elif [ "$sys_interface_available" = 0 ]; then
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@ -6367,13 +6424,20 @@ check_CVE_2023_20569_linux() {
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if ! is_cpu_affected "$cve" ; then
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# override status & msg in case CPU is not vulnerable after all
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pvulnstatus "$cve" OK "your CPU vendor reported your CPU model as not affected"
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elif [ "$cpu_family" = $(( 0x17 )) ] && [ "$smt_enabled" = 1 ] && [ -n "$cpuid_ibpb" ]; then
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pvulnstatus "$cve" OK "IBPB supported and SMT is off"
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elif [ "$cpu_family" = $(( 0x17 )) ]; then
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if [ "$smt_enabled" = 1 ] && [ -n "$cpuid_ibpb" ]; then
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pvulnstatus "$cve" OK "IBPB supported and SMT is off"
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elif [ "$smt_enabled" != 1 ] && [ -n "$cpuid_ibpb" ]; then
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pvulnstatus "$cve" VULN "SMT is enabled"
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elif [ "$smt_enabled" = 1 ]; then
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pvulnstatus "$cve" VULN "IBPB is not supported by your current microcode"
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else
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pvulnstatus "$cve" VULN "SMT is enabled and IBPB is not support by your current microcode"
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fi
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explain "Zen1/2 with SMT off aren't vulnerable after the right IBPB microcode has been applied. (https://github.com/torvalds/linux/commit/138bcddb86d8a4f842e4ed6f0585abc9b1a764ff#diff-17bd24a7a7850613cced545790ac30646097e8d6207348c2bd1845f397acb390R2272)"
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elif [ -z "$msg" ]; then
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# if msg is empty, sysfs check didn't fill it, rely on our own test
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# TODO
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pvulnstatus "$cve" UNK "further checks are required (WIP)"
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# if msg is empty, sysfs check didn't fill it. If the kernel does not bring the mitigation, system vuln.
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pvulnstatus $cve VULN "upgrade your kernel"
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else
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pvulnstatus $cve "$status" "$msg"
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fi
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