On Wed, Jun 3, 2020 at 4:24 PM Christian Brauner
[off-list ref] wrote:

Ok, here's what I have. Does the below look somewhat sane?

Probably. Needs lots of testing. But this one looks wrong:

+int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)
 {
+               if ((max_fd + 1) >= cur_max)
+                       max_unshare_fds = fd;

A normal value for "close everything starting at X" would have a
max_fd value of ~0.

So "max_fd+1" would overflow to 0, and then this would never trigger.

Other than that it looks what what I imagine my feverdreams were about.

              Linus