CVE-2021-46928

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> parisc: Clear stale IIR value on instruction access rights trap<br /> <br /> When a trap 7 (Instruction access rights) occurs, this means the CPU<br /> couldn&amp;#39;t execute an instruction due to missing execute permissions on<br /> the memory region. In this case it seems the CPU didn&amp;#39;t even fetched<br /> the instruction from memory and thus did not store it in the cr19 (IIR)<br /> register before calling the trap handler. So, the trap handler will find<br /> some random old stale value in cr19.<br /> <br /> This patch simply overwrites the stale IIR value with a constant magic<br /> "bad food" value (0xbaadf00d), in the hope people don&amp;#39;t start to try to<br /> understand the various random IIR values in trap 7 dumps.