From: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 1995266727fa8143897e89b55f5d3c79aa828420 ]
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@xxxxxxxxxxxxxxx>
Acked-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
fs/nfsd/auth.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c
index a260060042ad..67eb154af881 100644
--- a/fs/nfsd/auth.c
+++ b/fs/nfsd/auth.c
@@ -60,9 +60,10 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
else
GROUP_AT(gi, i) = GROUP_AT(rqgi, i);
- /* Each thread allocates its own gi, no race */
- groups_sort(gi);
}
+
+ /* Each thread allocates its own gi, no race */
+ groups_sort(gi);
} else {
gi = get_group_info(rqgi);
}
--
2.14.1