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spectre-meltdown-checker/src/vulns/CVE-2023-20569.sh
2026-03-31 20:16:47 +00:00

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# vim: set ts=4 sw=4 sts=4 et:
#######################
# Inception section
# CVE-2023-20569 Inception (SRSO, speculative return stack overflow) - entry point
check_CVE_2023_20569() {
check_cve 'CVE-2023-20569'
}
# CVE-2023-20569 Inception (SRSO, speculative return stack overflow) - Linux mitigation check
check_CVE_2023_20569_linux() {
local status sys_interface_available msg kernel_sro kernel_sro_err kernel_srso kernel_ibpb_entry smt_enabled
status=UNK
sys_interface_available=0
msg=''
if sys_interface_check "$VULN_SYSFS_BASE/spec_rstack_overflow"; then
# this kernel has the /sys interface, trust it over everything
sys_interface_available=1
status=$ret_sys_interface_check_status
fi
if [ "$opt_sysfs_only" != 1 ]; then
pr_info_nol "* Kernel supports mitigation: "
if [ -n "$g_kernel_err" ]; then
kernel_sro_err="$g_kernel_err"
elif grep -q 'spec_rstack_overflow' "$g_kernel"; then
kernel_sro="found spec_rstack_overflow in kernel image"
fi
if [ -n "$kernel_sro" ]; then
pstatus green YES "$kernel_sro"
elif [ -n "$kernel_sro_err" ]; then
pstatus yellow UNKNOWN "$kernel_sro_err"
else
pstatus yellow NO
fi
pr_info_nol "* Kernel compiled with SRSO support: "
if [ -r "$opt_config" ]; then
# CONFIG_CPU_SRSO: Linux < 6.9
# CONFIG_MITIGATION_SRSO: Linux >= 6.9
if grep -Eq '^CONFIG_(CPU|MITIGATION)_SRSO=y' "$opt_config"; then
pstatus green YES
kernel_srso="CONFIG_(CPU|MITIGATION)_SRSO=y found in kernel config"
else
pstatus yellow NO "required for safe RET and ibpb_on_vmexit mitigations"
fi
else
# https://github.com/torvalds/linux/commit/138bcddb86d8a4f842e4ed6f0585abc9b1a764ff#diff-17bd24a7a7850613cced545790ac30646097e8d6207348c2bd1845f397acb390R2313
if [ -n "$g_kernel_err" ]; then
pstatus yellow UNKNOWN "$g_kernel_err"
elif grep -Eq 'WARNING: kernel not compiled with (CPU|MITIGATION)_SRSO' "$g_kernel"; then
# this msg is optimized out at compile time if the option is not enabled, see commit referenced above
# if it's present, then SRSO is NOT compiled in
pstatus yellow NO "kernel not compiled with (CPU|MITIGATION)_SRSO"
else
# if it's not present, then SRSO is compiled in IF kernel_sro==1, otherwise we're just
# in front of an old kernel that doesn't have the mitigation logic at all
if [ "$kernel_sro" = 1 ]; then
kernel_srso="SRSO mitigation logic is compiled in the kernel"
pstatus green OK "$kernel_srso"
else
pstatus yellow NO "your kernel is too old and doesn't have the mitigation logic"
fi
fi
fi
pr_info_nol "* Kernel compiled with IBPB_ENTRY support: "
if [ -r "$opt_config" ]; then
# CONFIG_CPU_IBPB_ENTRY: Linux < 6.9
# CONFIG_MITIGATION_IBPB_ENTRY: Linux >= 6.9
if grep -Eq '^CONFIG_(CPU|MITIGATION)_IBPB_ENTRY=y' "$opt_config"; then
pstatus green YES
kernel_ibpb_entry="CONFIG_(CPU|MITIGATION)_IBPB_ENTRY=y found in kernel config"
else
pstatus yellow NO
fi
else
# https://github.com/torvalds/linux/commit/138bcddb86d8a4f842e4ed6f0585abc9b1a764ff#diff-17bd24a7a7850613cced545790ac30646097e8d6207348c2bd1845f397acb390R2325
if [ -n "$g_kernel_err" ]; then
pstatus yellow UNKNOWN "$g_kernel_err"
elif grep -Eq 'WARNING: kernel not compiled with (CPU|MITIGATION)_IBPB_ENTRY' "$g_kernel"; then
# this msg is optimized out at compile time if the option is not enabled, see commit referenced above
# if it's present, then IBPB_ENTRY is NOT compiled in
pstatus yellow NO "kernel not compiled with (CPU|MITIGATION)_IBPB_ENTRY"
else
# if it's not present, then IBPB_ENTRY is compiled in IF kernel_sro==1, otherwise we're just
# in front of an old kernel that doesn't have the mitigation logic at all
if [ "$kernel_sro" = 1 ]; then
kernel_ibpb_entry="IBPB_ENTRY mitigation logic is compiled in the kernel"
pstatus green OK "$kernel_ibpb_entry"
else
pstatus yellow NO "your kernel is too old and doesn't have the mitigation logic"
fi
fi
fi
# Zen & Zen2 : if the right IBPB microcode applied + SMT off --> not vuln
if [ "$cpu_family" = $((0x17)) ]; then
pr_info_nol "* CPU supports IBPB: "
if [ -n "$cap_ibpb" ]; then
pstatus green YES "$cap_ibpb"
else
pstatus yellow NO
fi
pr_info_nol "* Hyper-Threading (SMT) is enabled: "
is_cpu_smt_enabled
smt_enabled=$?
if [ "$smt_enabled" = 0 ]; then
pstatus yellow YES
else
pstatus green NO
fi
# Zen 3/4 microcode brings SBPB mitigation
elif [ "$cpu_family" = $((0x19)) ]; then
pr_info_nol "* CPU supports SBPB: "
if [ "$cap_sbpb" = 1 ]; then
pstatus green YES
elif [ "$cap_sbpb" = 3 ]; then
pstatus yellow UNKNOWN "cannot write MSR, rerun with --allow-msr-write"
else
pstatus yellow NO
fi
fi
elif [ "$sys_interface_available" = 0 ]; then
# we have no sysfs but were asked to use it only!
msg="/sys vulnerability interface use forced, but it's not available!"
status=UNK
fi
if ! is_cpu_affected "$cve"; then
# override status & msg in case CPU is not vulnerable after all
pvulnstatus "$cve" OK "your CPU vendor reported your CPU model as not affected"
elif [ -z "$msg" ]; then
# if msg is empty, sysfs check didn't fill it, so we rely on our own logic
# Zen/Zen2
if [ "$cpu_family" = $((0x17)) ]; then
if [ "$smt_enabled" = 0 ]; then
pvulnstatus "$cve" VULN "SMT is enabled on your Zen/Zen2 CPU, which makes mitigation ineffective"
explain "For Zen/Zen2 CPUs, proper mitigation needs an up to date microcode, and SMT needs to be disabled (this can be done by adding \`nosmt\` to your kernel command line)"
elif [ -z "$kernel_sro" ]; then
pvulnstatus "$cve" VULN "Your kernel is too old and doesn't have the SRSO mitigation logic"
elif [ -n "$cap_ibpb" ]; then
pvulnstatus "$cve" OK "SMT is disabled and both your kernel and microcode support mitigation"
else
pvulnstatus "$cve" VULN "Your microcode is too old"
fi
# Zen3/Zen4
elif [ "$cpu_family" = $((0x19)) ]; then
if [ -z "$kernel_sro" ]; then
pvulnstatus "$cve" VULN "Your kernel is too old and doesn't have the SRSO mitigation logic"
elif [ -z "$kernel_srso" ] && [ -z "$kernel_ibpb_entry" ]; then
pvulnstatus "$cve" VULN "Your kernel doesn't have either SRSO or IBPB_ENTRY compiled-in"
elif [ "$cap_sbpb" = 3 ]; then
pvulnstatus "$cve" UNK "Couldn't verify if your microcode supports IBPB (rerun with --allow-msr-write)"
elif [ "$cap_sbpb" = 2 ]; then
pvulnstatus "$cve" VULN "Your microcode doesn't support SBPB"
else
pvulnstatus "$cve" OK "Your kernel and microcode both support mitigation"
fi
else
# not supposed to happen, as normally this CPU should not be affected and not run this code
pvulnstatus "$cve" OK "your CPU vendor reported your CPU model as not affected"
fi
else
pvulnstatus "$cve" "$status" "$msg"
fi
}