linux-kernel - [PATCH] nfsd: make a copy of struct iattr before calling notify

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Date:   Wed, 17 May 2023 12:26:44 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Chuck Lever <chuck.lever@...cle.com>
Cc:     Zhi Li <yieli@...hat.com>, linux-nfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] nfsd: make a copy of struct iattr before calling notify_change

notify_change can modify the iattr structure. In particular it can 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.

Fixes: 34b91dda7124 NFSD: Make nfsd4_setattr() wait before returning NFS4ERR_DELAY
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2207969
Reported-by: Zhi Li <yieli@...hat.com>
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/nfsd/vfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index c4ef24c5ffd0..ad0c5cd900b1 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -538,7 +538,9 @@ 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 = *iap;
+
+		host_err = __nfsd_setattr(dentry, &attrs);
 		if (host_err != -EAGAIN || !retries--)
 			break;
 		if (!nfsd_wait_for_delegreturn(rqstp, inode))
-- 
2.40.1