nfsd: auth: Fix gid sorting when rootsquash enabled

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commit 1995266727 upstream.

Commit bdcf0a423e ("kernel: make groups_sort calling a responsibility
group_info allocators") appears to break nfsd rootsquash in a pretty
major way.

It adds a call to groups_sort() inside the loop that copies/squashes
gids, which means the valid gids are sorted along with the following
garbage.  The net result is that the highest numbered valid gids are
replaced with any lower-valued garbage gids, possibly including 0.

We should sort only once, after filling in all the gids.

Fixes: bdcf0a423e ("kernel: make groups_sort calling a responsibility ...")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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Ben Hutchings 2018-01-22 20:11:06 +00:00 • committed by Ben Hutchings

parent d92fb5824b

commit 76a90eeac5

1 changed files with 3 additions and 3 deletions

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