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From:   Scott Mayhew <smayhew@redhat.com>
To:     trond.myklebust@hammerspace.com, anna.schumaker@netapp.com
Cc:     syzbot <syzbot+193c375dcddb4f345091@syzkaller.appspotmail.com>,
        syzkaller-bugs@googlegroups.com, linux-nfs@vger.kernel.org
Subject: [PATCH] NFS: Fix leak of ctx->nfs_server.hostname
Date:   Tue, 25 Feb 2020 11:05:22 -0500
Message-Id: <20200225160522.225406-1-smayhew@redhat.com>
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Sender: linux-nfs-owner@vger.kernel.org
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If userspace passes an nfs_mount_data struct in the data argument of
mount(2), then nfs23_parse_monolithic() or nfs4_parse_monolithic()
will allocate memory for ctx->nfs_server.hostname.  This needs to be
freed in nfs_parse_source(), which also allocates memory for
ctx->nfs_server.hostname, otherwise a leak will occur.

Reported-by: syzbot+193c375dcddb4f345091@syzkaller.appspotmail.com
Fixes: f2aedb713c28 ("NFS: Add fs_context support.")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 fs/nfs/fs_context.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index b616263b0eb6..e113fcb4bb4c 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -832,6 +832,8 @@ static int nfs_parse_source(struct fs_context *fc,
 	if (len > maxnamlen)
 		goto out_hostname;
=20
+	kfree(ctx->nfs_server.hostname);
+
 	/* N.B. caller will free nfs_server.hostname in all cases */
 	ctx->nfs_server.hostname =3D kmemdup_nul(dev_name, len, GFP_KERNEL);
 	if (!ctx->nfs_server.hostname)
--=20
2.24.1