CVE-2024-42233

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> filemap: replace pte_offset_map() with pte_offset_map_nolock()<br /> <br /> The vmf-&gt;ptl in filemap_fault_recheck_pte_none() is still set from<br /> handle_pte_fault(). But at the same time, we did a pte_unmap(vmf-&gt;pte). <br /> After a pte_unmap(vmf-&gt;pte) unmap and rcu_read_unlock(), the page table<br /> may be racily changed and vmf-&gt;ptl maybe fails to protect the actual page<br /> table. Fix this by replacing pte_offset_map() with<br /> pte_offset_map_nolock().<br /> <br /> As David said, the PTL pointer might be stale so if we continue to use<br /> it infilemap_fault_recheck_pte_none(), it might trigger UAF. Also, if<br /> the PTL fails, the issue fixed by commit 58f327f2ce80 ("filemap: avoid<br /> unnecessary major faults in filemap_fault()") might reappear.