Merge tag 'for-linus-2021-04-08' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull close_range() fix from Christian Brauner:
"Syzbot reported a bug in close_range.
Debugging this showed we didn't recalculate the current maximum fd
number for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC after we unshared
the file descriptors table. As a result, max_fd could exceed the
current fdtable maximum causing us to set excessive bits.
As a concrete example, let's say the user requested everything from fd
4 to ~0UL to be closed and their current fdtable size is 256 with
their highest open fd being 4. With CLOSE_RANGE_UNSHARE the caller
will end up with a new fdtable which has room for 64 file descriptors
since that is the lowest fdtable size we accept. But now max_fd will
still point to 255 and needs to be adjusted. Fix this by retrieving
the correct maximum fd value in __range_cloexec().
I've carried this fix for a little while but since there was no
linux-next release over easter I waited until now.
With this change close_range() can be further simplified but imho we
are in no hurry to do that and so I'll defer this for the 5.13 merge
* tag 'for-linus-2021-04-08' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
file: fix close_range() for unshare+cloexec