linux-kernel - [PATCH 4.9 01/90] NFS: Remove superfluous kmap in nfs_readdir_xdr_to

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Date:   Thu, 19 Mar 2020 13:59:23 +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, Petr Malat <oss@...at.biz>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 01/90] NFS: Remove superfluous kmap in nfs_readdir_xdr_to_array

From: Petr Malat <oss@...at.biz>

Array is mapped by nfs_readdir_get_array(), the further kmap is a result
of a bad merge and should be removed.

This resource leakage can be exploited for DoS by receptively reading
a content of a directory on NFS (e.g. by running ls).

Fixes: 67a56e9743171 ("NFS: Fix memory leaks and corruption in readdir")
Signed-off-by: Petr Malat <oss@...at.biz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/nfs/dir.c |    2 --
 1 file changed, 2 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -678,8 +678,6 @@ int nfs_readdir_xdr_to_array(nfs_readdir
 		goto out_label_free;
 	}
 
-	array = kmap(page);
-
 	status = nfs_readdir_alloc_pages(pages, array_size);
 	if (status < 0)
 		goto out_release_array;