linux-kernel - [PATCH AUTOSEL 5.4 15/15] nfsd: zero out pointers after putting nfsd

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Message-Id: <20230227021038.1052958-15-sashal@kernel.org>
Date:   Sun, 26 Feb 2023 21:10:34 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jeff Layton <jlayton@...nel.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Sasha Levin <sashal@...nel.org>, linux-nfs@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 15/15] nfsd: zero out pointers after putting nfsd_files on COPY setup error

From: Jeff Layton <jlayton@...nel.org>

[ Upstream commit 1f0001d43d0c0ac2a19a34a914f6595ad97cbc1d ]

At first, I thought this might be a source of nfsd_file overputs, but
the current callers seem to avoid an extra put when nfsd4_verify_copy
returns an error.

Still, it's "bad form" to leave the pointers filled out when we don't
have a reference to them anymore, and that might lead to bugs later.
Zero them out as a defensive coding measure.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nfsd/nfs4proc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 452ed633a2c76..bd7846758947b 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1059,8 +1059,10 @@ nfsd4_verify_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	return status;
 out_put_dst:
 	nfsd_file_put(*dst);
+	*dst = NULL;
 out_put_src:
 	nfsd_file_put(*src);
+	*src = NULL;
 	goto out;
 }
 
-- 
2.39.0