udf: Avoid run away loop when partition table length is corrupted
authorJan Kara <jack@suse.cz>
Wed, 27 Jun 2012 18:20:22 +0000 (20:20 +0200)
committerJan Kara <jack@suse.cz>
Thu, 28 Jun 2012 17:30:58 +0000 (19:30 +0200)
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

index 9da6f4ee112c8b46044806002d29f49964313cc3..ce911f50b39d8de9c1e627c0aa1173d37c330341 100644 (file)
@@ -1225,6 +1225,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
        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);
@@ -1232,13 +1233,20 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
                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_err(sb, "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 *)