[PATCH 4.18 143/145] udf: Fix mounting of Win7 created UDF filesystems

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Jan Kara <jack@xxxxxxx>

commit ee4af50ca94f58afc3532662779b9cf80bbe27c8 upstream.

Win7 is creating UDF filesystems with single partition with number 8192.
Current partition descriptor scanning code does not handle this well as
it incorrectly assumes that partition numbers will form mostly contiguous
space of small numbers. This results in unmountable media due to errors
like:

UDF-fs: error (device dm-1): udf_read_tagged: tag version 0x0000 != 0x0002 || 0x0003, block 0
UDF-fs: warning (device dm-1): udf_fill_super: No fileset found

Fix the problem by handling partition descriptors in a way that sparse
partition numbering does not matter.

Reported-and-tested-by: jean-luc malet <jeanluc.malet@xxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Fixes: 7b78fd02fb19530fd101ae137a1f46aa466d9bb6
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/udf/super.c |   31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1570,10 +1570,16 @@ static void udf_load_logicalvolint(struc
  */
 #define PART_DESC_ALLOC_STEP 32
 
+struct part_desc_seq_scan_data {
+	struct udf_vds_record rec;
+	u32 partnum;
+};
+
 struct desc_seq_scan_data {
 	struct udf_vds_record vds[VDS_POS_LENGTH];
 	unsigned int size_part_descs;
-	struct udf_vds_record *part_descs_loc;
+	unsigned int num_part_descs;
+	struct part_desc_seq_scan_data *part_descs_loc;
 };
 
 static struct udf_vds_record *handle_partition_descriptor(
@@ -1582,10 +1588,14 @@ static struct udf_vds_record *handle_par
 {
 	struct partitionDesc *desc = (struct partitionDesc *)bh->b_data;
 	int partnum;
+	int i;
 
 	partnum = le16_to_cpu(desc->partitionNumber);
-	if (partnum >= data->size_part_descs) {
-		struct udf_vds_record *new_loc;
+	for (i = 0; i < data->num_part_descs; i++)
+		if (partnum == data->part_descs_loc[i].partnum)
+			return &(data->part_descs_loc[i].rec);
+	if (data->num_part_descs >= data->size_part_descs) {
+		struct part_desc_seq_scan_data *new_loc;
 		unsigned int new_size = ALIGN(partnum, PART_DESC_ALLOC_STEP);
 
 		new_loc = kcalloc(new_size, sizeof(*new_loc), GFP_KERNEL);
@@ -1597,7 +1607,7 @@ static struct udf_vds_record *handle_par
 		data->part_descs_loc = new_loc;
 		data->size_part_descs = new_size;
 	}
-	return &(data->part_descs_loc[partnum]);
+	return &(data->part_descs_loc[data->num_part_descs++].rec);
 }
 
 
@@ -1647,6 +1657,7 @@ static noinline int udf_process_sequence
 
 	memset(data.vds, 0, sizeof(struct udf_vds_record) * VDS_POS_LENGTH);
 	data.size_part_descs = PART_DESC_ALLOC_STEP;
+	data.num_part_descs = 0;
 	data.part_descs_loc = kcalloc(data.size_part_descs,
 				      sizeof(*data.part_descs_loc),
 				      GFP_KERNEL);
@@ -1658,7 +1669,6 @@ static noinline int udf_process_sequence
 	 * are in it.
 	 */
 	for (; (!done && block <= lastblock); block++) {
-
 		bh = udf_read_tagged(sb, block, block, &ident);
 		if (!bh)
 			break;
@@ -1730,13 +1740,10 @@ static noinline int udf_process_sequence
 	}
 
 	/* Now handle prevailing Partition Descriptors */
-	for (i = 0; i < data.size_part_descs; i++) {
-		if (data.part_descs_loc[i].block) {
-			ret = udf_load_partdesc(sb,
-						data.part_descs_loc[i].block);
-			if (ret < 0)
-				return ret;
-		}
+	for (i = 0; i < data.num_part_descs; i++) {
+		ret = udf_load_partdesc(sb, data.part_descs_loc[i].rec.block);
+		if (ret < 0)
+			return ret;
 	}
 
 	return 0;