On Mon, Feb 15, 2021 at 09:53:05AM -0500, Alex Xu (Hello71) wrote:

Since maxlen is already exposed, we can allocate approximately the right
amount directly, fixing up those drivers which set a bogus maxlen. These
drivers were located based on those which had copy_x_user replaced in
32927393dc1c, on the basis that other drivers either use builtin proc_*
handlers, or do not access the data pointer. The latter is OK because
maxlen only needs to be an upper limit.

Please split this into one patch each each subsystem that sets maxlen
to 0 and the actual change to proc_sysctl.c.

How do these maxlen = 0 entries even survive the sysctl_check_table
check?