nfsd: make a copy of struct iattr before calling notify_change

notify_change can modify the iattr structure. In particular it can
end up setting ATTR_MODE when ATTR_KILL_SUID is already set, causing
a BUG() if the same iattr is passed to notify_change more than once.

Make a copy of the struct iattr before calling notify_change.

Reported-by: Zhi Li <yieli@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2207969
Tested-by: Zhi Li <yieli@redhat.com>
Fixes: 34b91dda7124 ("NFSD: Make nfsd4_setattr() wait before returning NFS4ERR_DELAY")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index bb9d471721623607061a86ea666d4e0dedb596dc..db67f8e19344a454dbc8aa8166fe362ef156145d 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -536,7 +536,15 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
        inode_lock(inode);
        for (retries = 1;;) {
-               host_err = __nfsd_setattr(dentry, iap);
+               struct iattr attrs;
+
+               /*
+                * notify_change() can alter its iattr argument, making
+                * @iap unsuitable for submission multiple times. Make a
+                * copy for every loop iteration.
+                */
+               attrs = *iap;
+               host_err = __nfsd_setattr(dentry, &attrs);
                if (host_err != -EAGAIN || !retries--)
                        break;
                if (!nfsd_wait_for_delegreturn(rqstp, inode))