Commit 08841b06 authored by Seohyeon Maeng's avatar Seohyeon Maeng Committed by Jan Kara
Browse files

udf: fix partition descriptor append bookkeeping 



Mounting a crafted UDF image with repeated partition descriptors can
trigger a heap out-of-bounds write in part_descs_loc[].

handle_partition_descriptor() deduplicates entries by partition number,
but appended slots never record partnum. As a result duplicate
Partition Descriptors are appended repeatedly and num_part_descs keeps
growing.

Once the table is full, the growth path still sizes the allocation from
partnum even though inserts are indexed by num_part_descs. If partnum is
already aligned to PART_DESC_ALLOC_STEP, ALIGN(partnum, step) can keep
the old capacity and the next append writes past the end of the table.

Store partnum in the appended slot and size growth from the next append
count so deduplication and capacity tracking follow the same model.

Fixes: ee4af50c ("udf: Fix mounting of Win7 created UDF filesystems")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSeohyeon Maeng <bioloidgp@gmail.com>
Link: https://patch.msgid.link/20260310081652.21220-1-bioloidgp@gmail.com


Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 19134a13

fs/udf/super.c

+3 −1
Original line number Diff line number Diff line
@@ -1694,8 +1694,9 @@ static struct udf_vds_record *handle_partition_descriptor( 
			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);

		unsigned int new_size;



		new_size = data->num_part_descs + PART_DESC_ALLOC_STEP;

		new_loc = kzalloc_objs(*new_loc, new_size);

		if (!new_loc)

			return ERR_PTR(-ENOMEM);
@@ -1705,6 +1706,7 @@ static struct udf_vds_record *handle_partition_descriptor( 
		data->part_descs_loc = new_loc;

		data->size_part_descs = new_size;

	}

	data->part_descs_loc[data->num_part_descs].partnum = partnum;

	return &(data->part_descs_loc[data->num_part_descs++].rec);

}