From: Ben Hutchings ben.hutchings@codethink.co.uk
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ 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@codethink.co.uk Acked-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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); }