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udf: Avoid run away loop when partition table length is corrupted

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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>
This commit is contained in:
Jan Kara 2012-06-27 20:20:22 +02:00
parent cb14d340ef
commit adee11b208
1 changed files with 9 additions and 1 deletions
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10
fs/udf/super.c
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@ -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 *)