[PATCH 5/7] knfsd: only set ATTR_KILL_S*ID if ATTR_MODE isn't being explicitly set

[Jeff Layton]

It's theoretically possible for a single SETATTR call to come in that
sets the mode and the uid/gid. In that case, assume the mode is
correct and don't set the ATTR_KILL_S*ID bits. Doing so would trip the
BUG() in notify_change.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/nfsd/vfs.c |   17 +++++++++++------
 1 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 70f2c86..3b5b8cf 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -369,14 +369,19 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
 	if (iap->ia_valid & ATTR_MODE) {
 		iap->ia_mode &= S_IALLUGO;
 		imode = iap->ia_mode |= (imode & ~S_IALLUGO);
+		if ((iap->ia_valid & ATTR_UID) && iap->ia_uid != inode->i_uid)
+			iap->ia_valid |= ATTR_KILL_PRIV;
+	} else {
+		/*
+		 * Revoke setuid/setgid bit on chown/chgrp, unless the mode
+		 * is being explicitly set
+		 */
+		if ((iap->ia_valid & ATTR_UID) && iap->ia_uid != inode->i_uid)
+			iap->ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV;
+		if ((iap->ia_valid & ATTR_GID) && iap->ia_gid != inode->i_gid)
+			iap->ia_valid |= ATTR_KILL_SGID;
 	}
 
-	/* Revoke setuid/setgid bit on chown/chgrp */
-	if ((iap->ia_valid & ATTR_UID) && iap->ia_uid != inode->i_uid)
-		iap->ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV;
-	if ((iap->ia_valid & ATTR_GID) && iap->ia_gid != inode->i_gid)
-		iap->ia_valid |= ATTR_KILL_SGID;
-
 	/* Change the attributes. */
 
 	iap->ia_valid |= ATTR_CTIME;
-- 
1.5.2.1

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