The 11/01/2022 12:19, David Laight wrote:

From: 'Szabolcs Nagy' <redacted>

quoted

SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
{

That is just a wrapper and calls do_fcntl().
which needs changing to be add:
	arg &= ~0U;
before the switch(cmd) {

this makes sense.
i thought previously you meant masking in userspace.

although if you mask there then many linux internal
apis could use int instead of long arg.

do you want me to post a patch? (i'm not a kernel
developer)