Commit f12d0602 authored Jan 22, 2018 by Ben Hutchings Committed by Greg Kroah-Hartman Jan 31, 2018

nfsd: auth: Fix gid sorting when rootsquash enabled



commit 1995266727fa8143897e89b55f5d3c79aa828420 upstream.

Commit bdcf0a423ea1 ("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: bdcf0a423ea1 ("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>
Cc: Wolfgang Walter <linux@stwm.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent f531fbb0

fs/nfsd/auth.c

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -59,10 +59,10 @@ int nfsd_setuser(struct svc_rqst rqstp, struct svc_export exp)
	gi->gid[i] = exp->ex_anon_gid;		gi->gid[i] = exp->ex_anon_gid;
	else		else
	gi->gid[i] = rqgi->gid[i];		gi->gid[i] = rqgi->gid[i];
			}

	/* Each thread allocates its own gi, no race */		/* Each thread allocates its own gi, no race */
	groups_sort(gi);		groups_sort(gi);
	}
	} else {		} else {
	gi = get_group_info(rqgi);		gi = get_group_info(rqgi);
	}		}