[v2.6.34-stable 60/77] udf: Avoid run away loop when partition table length is corrupted

Paul Gortmaker
2013-01-08T23:40:28Z

From: Jan Kara <jack@suse.cz>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit adee11b2085bee90bd8f4f52123ffb07882d6256 upstream.

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>
[PG: in 2.6.34 udf_err() is called udf_error()]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/udf/super.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 4551ad2..a48725b 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1298,6 +1298,7 @@ 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);
@@ -1305,6 +1306,13 @@ 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_error(sb, "error loading logical volume descriptor: "
+ "Partition table too long (%u > %lu)\n", table_len,
+ sb->s_blocksize - sizeof(*lvd));
+ goto out_bh;
+ }

i = udf_sb_alloc_partition_maps(sb, le32_to_cpu(lvd->numPartitionMaps));
if (i != 0) {
@@ -1313,7 +1321,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
}

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 *)
--
1.7.12.1