UBUNTU-CVE-2026-52933: High severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: iouring/poll: fix signed comparison in iopollgetownership() iopollgetownership() uses a signed comparison to check whether pollrefs has reached the threshold for the slowpath: if (unlikely(atomicread(&req->pollrefs) >= IOPOLLREFBIAS)) atomicread() returns int (signed). When IOPOLLCANCELFLAG (BIT(31)) is set in pollrefs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomicread() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath.