CVE-2021-46928

Summary

In the Linux kernel, the following vulnerability has been resolved:

parisc: Clear stale IIR value on instruction access rights trap

When a trap 7 (Instruction access rights) occurs, this means the CPU couldn't execute an instruction due to missing execute permissions on the memory region. In this case it seems the CPU didn't even fetched the instruction from memory and thus did not store it in the cr19 (IIR) register before calling the trap handler. So, the trap handler will find some random old stale value in cr19.

This patch simply overwrites the stale IIR value with a constant magic "bad food" value (0xbaadf00d), in the hope people don't start to try to understand the various random IIR values in trap 7 dumps.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < d01e9ce1af6116f812491d3d3873d204f10ae0b8affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e96373f0a5f484bc1e193f9951dcb3adf24bf3f7affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 484730e5862f6b872dca13840bed40fd7c60fa26affected
LinuxLinux2.6.12affected
LinuxLinux0 < 2.6.12unaffected
LinuxLinux5.10.90 <= 5.10.*unaffected
LinuxLinux5.15.13 <= 5.15.*unaffected
LinuxLinux5.16 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References