Commit 19952667 authored Jan 22, 2018 by Ben Hutchings Committed by Linus Torvalds Jan 22, 2018

nfsd: auth: Fix gid sorting when rootsquash enabled



Commit bdcf0a42 ("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: bdcf0a42 ("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>

parent a0ec1ded

fs/nfsd/auth.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -60,10 +60,10 @@ int nfsd_setuser(struct svc_rqst rqstp, struct svc_export exp)
		gi->gid[i] = exp->ex_anon_gid;
		else
		gi->gid[i] = rqgi->gid[i];
		}

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

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