On 2019-11-09 at 00:04 Michal Hocko wrote: >On Fri 08-11-19 23:49:29, Li Xinhai wrote: >> The maxnode used by mbind(), set_mempolicy() and migrate_pages() is not >> correctly handled in get_nodes(), where --maxnode cause the calculation >> endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1; >> ignores the highest node ID bit. Then, at >> nodes_addr(*nodes)[nlongs-1] &= endmask; >> the highest node ID bit is cleared. Finally, cause mpol_new() think user >> does not pass in any node ID, and return EINVAL. >> >> The results are: >> - Application receives EINVAL when only the highest node ID bit is set. >> - Application recevies no error when other bits set together with the >> highest node ID bit, but that highest ID is ignored. > >A similar patch has been posted [1] and rejected [2]. > >[1] http://lkml.kernel.org/r/1570882789-20579-1-git-send-email-zhangpan26@xxxxxxxxxx >[2] http://lkml.kernel.org/r/20191014091243.GD317@xxxxxxxxxxxxxx > > >-- >Michal Hocko >SUSE Labs I just checked the code in 'history' log for curiosity, this --maxnode seems appeared since the very first commit. Mention about this special point of maxnode in manpage of these three APIs would be one solution, :). Xinhai
