linux-kernel - [PATCH 5.9 144/255] NFSD: Fix use-after-free warning when doing inter-server copy

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Message-Id: <20201117122145.959037674@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:04:44 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dai Ngo <dai.ngo@...cle.com>,
        "J. Bruce Fields" <bfields@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 144/255] NFSD: Fix use-after-free warning when doing inter-server copy

From: Dai Ngo <dai.ngo@...cle.com>

[ Upstream commit 36e1e5ba90fb3fba6888fae26e4dfc28bf70aaf1 ]

The source file nfsd_file is not constructed the same as other
nfsd_file's via nfsd_file_alloc. nfsd_file_put should not be
called to free the object; nfsd_file_put is not the inverse of
kzalloc, instead kfree is called by nfsd4_do_async_copy when done.

Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy")
Signed-off-by: Dai Ngo <dai.ngo@...cle.com>
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nfsd/nfs4proc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 84e10aef14175..80effaa18b7b2 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1299,7 +1299,7 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct nfsd_file *src,
 			struct nfsd_file *dst)
 {
 	nfs42_ssc_close(src->nf_file);
-	nfsd_file_put(src);
+	/* 'src' is freed by nfsd4_do_async_copy */
 	nfsd_file_put(dst);
 	mntput(ss_mnt);
 }
-- 
2.27.0