Hi Oleg,
>> >> No. Yes, deny_write_access() protects mm->exe_file, but not the dynamic >> libraries or other files which can be mmaped. > > I see. Let me see how we can cover this. > >> >>>> and I am worried this code can try to lock the same page twice... >>>> Say, the probed application does MADV_DONTNEED and then writes "int3" >>>> into vma->vm_file at the same address to fool verify_opcode(). >>>> >>> >>> Do you mean the case where old_page == new_page? >> >> Yes, >> >>> I think this won't >>> happen, because in uprobe_write_opcode() we only do orig_page for >>> !is_register case. >> >> See above. >> >> !is_register doesn't necessarily mean the original page was previously >> cow'ed. >> And even if it was cow'ed, MADV_DONTNEED can restore the original mapping. > > I guess I know the case now. We can probably avoid this with an simple > check for old_page == new_page? I decided to follow your suggestion of "unmap old_page; fault in orig_page". Please see v9 of the set. Thanks, Song
