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speed47 / spectre-meltdown-checker

Reptar, Downfall, Zenbleed, ZombieLoad, RIDL, Fallout, Foreshadow, Spectre, Meltdown vulnerability/mitigation checker for Linux & BSD
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please add grsecurity UDEREF detection #148

Closed emcepe closed 6 years ago

emcepe commented 6 years ago

Hi,

grsecurity's PaX adds UDEREF for a long time now and its also a full replacement for mainline PTI - it does everything PTI does (better) and does everything UDEREF used to do in the past.

Please find my attached patch suggestion. spectre-meltdown-checker.sh-grsecurity-PaX.patch.zip

speed47 commented 6 years ago

Hello,

Your patch would imply false positives: you're only looking for the UDEREF option, however it has only been patched recently by spender to include mitigation for Meltdown : checking for UDEREF is not enough.

Fortunately, spender included in his patch a flag exported to the /sys fs hierarchy to notify userspace than the kernel has been compiled with a recent enough version of UDEREF that protects from Meltdown. This check is already implemented in the script.

Excerpt of output under grsec:

CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'

  • Mitigated according to the /sys interface: YES (kernel confirms that the mitigation is active)
  • Kernel supports Page Table Isolation (PTI): NO
  • PTI enabled and active: UNKNOWN (dmesg truncated, please reboot and relaunch this script)
  • Running as a Xen PV DomU: NO

    STATUS: NOT VULNERABLE (Mitigation: PAX_UDEREF)

speed47 commented 6 years ago

Closing this issue as I consider it resolved. Please reopen if needed.