[PATCH 2/3] udf: Avoid run away loop when partition table length is corrupted

[Jan Kara <jack@suse.cz>]

Check provided length of partition table so that (possibly maliciously)
corrupted partition table cannot cause accessing data beyond current buffer.

Signed-off-by: Jan Kara <jack@suse.cz>

---
 fs/udf/super.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

Index: linux-3.0-SLE11-SP2/fs/udf/super.c
===================================================================
--- linux-3.0-SLE11-SP2.orig/fs/udf/super.c
+++ linux-3.0-SLE11-SP2/fs/udf/super.c
@@ -1254,6 +1254,7 @@ static int udf_load_logicalvol(struct su
 	struct genericPartitionMap *gpm;
 	uint16_t ident;
 	struct buffer_head *bh;
+	unsigned int table_len;
 	int ret = 0;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
@@ -1261,13 +1262,20 @@ static int udf_load_logicalvol(struct su
 		return 1;
 	BUG_ON(ident != TAG_IDENT_LVD);
 	lvd = (struct logicalVolDesc *)bh->b_data;
+	table_len = le32_to_cpu(lvd->mapTableLength);
+	if (sizeof(*lvd) + table_len > sb->s_blocksize) {
+		udf_error(sb, __func__, "error loading logical volume descriptor: "
+			"Partition table too long (%u > %lu)\n", table_len,
+			sb->s_blocksize - sizeof(*lvd));
+		goto out_bh;
+	}
 
 	ret = udf_sb_alloc_partition_maps(sb, le32_to_cpu(lvd->numPartitionMaps));
 	if (ret)
 		goto out_bh;
 
 	for (i = 0, offset = 0;
-	     i < sbi->s_partitions && offset < le32_to_cpu(lvd->mapTableLength);
+	     i < sbi->s_partitions && offset < table_len;
 	     i++, offset += gpm->partitionMapLength) {
 		struct udf_part_map *map = &sbi->s_partmaps[i];
 		gpm = (struct genericPartitionMap *)