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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Anatoly Trosinenko <anatoly.trosinenko@gmail.com>,
        Jan Kara <jack@suse.cz>
Subject: [PATCH 4.17 195/220] udf: Detect incorrect directory size
Date:   Sun,  1 Jul 2018 18:23:39 +0200
Message-Id: <20180701160916.330434753@linuxfoundation.org>
In-Reply-To: <20180701160908.272447118@linuxfoundation.org>
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4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@suse.cz>

commit fa65653e575fbd958bdf5fb9c4a71a324e39510d upstream.

Detect when a directory entry is (possibly partially) beyond directory
size and return EIO in that case since it means the filesystem is
corrupted. Otherwise directory operations can further corrupt the
directory and possibly also oops the kernel.

CC: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
CC: stable@vger.kernel.org
Reported-and-tested-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/udf/directory.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/udf/directory.c
+++ b/fs/udf/directory.c
@@ -152,6 +152,9 @@ struct fileIdentDesc *udf_fileident_read
 			       sizeof(struct fileIdentDesc));
 		}
 	}
+	/* Got last entry outside of dir size - fs is corrupted! */
+	if (*nf_pos > dir->i_size)
+		return NULL;
 	return fi;
 }