Bugzilla – Bug 1220480
VUL-0: CVE-2021-46928: kernel: parisc: Clear stale IIR value on instruction access rights trap
Last modified: 2024-05-16 04:44:06 UTC
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. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-46928 https://git.kernel.org/stable/c/d01e9ce1af6116f812491d3d3873d204f10ae0b8 https://git.kernel.org/stable/c/e96373f0a5f484bc1e193f9951dcb3adf24bf3f7 https://www.cve.org/CVERecord?id=CVE-2021-46928 https://git.kernel.org/stable/c/484730e5862f6b872dca13840bed40fd7c60fa26